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  • 301.
    Ektarawong, Annop
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    First-principles study of configurational disorder in B4C using a superatom-special quasirandom structure method2014Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, nr 2, artikel-id 024204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Configurationally disordered crystalline boron carbide, with the composition B4C, is studied using first-principles calculations. We investigate both dilute and high concentrations of carbon-boron substitutional defects. For the latter purpose, we suggest a superatoms picture of the complex structure and combine it with a special quasirandom structure approach for disorder. In this way, we model a random distribution of high concentrations of the identified low-energy defects: (1) bipolar defects and (2) rotation of icosahedral carbon among the three polar-up sites. Additionally, the substitutional disorder of the icosahedral carbon at all six polar sites, as previously discussed in the literature, is also considered. Two configurational phase transitions from the ordered to the disordered configurations are predicted to take place upon an increase in temperature using a mean-field approximation for the entropy. The first transition, at 870 K, induces substitutional disorder of the icosahedral carbon atoms among the three polar-up sites; meanwhile the second transition, at 2325 K, reveals the random substitution of the icosahedral carbon atoms at all six polar sites coexisting with bipolar defects. Already the first transition removes the monoclinic distortion existing in the ordered ground-state configuration and restore the rhombohedral system (R3m). The restoration of inversion symmetry yielding the full rhombohedral symmetry (R (3) over barm) on average, corresponding to what is reported in the literature, is achieved after the second transition. Investigating the effects of high pressure on the configurational stability of the disordered B4C phases reveals a tendency to stabilize the ordered ground-state configuration as the configurationally ordering/disordering transition temperature increases with pressure exerted on B4C. The electronic density of states, obtained from the disordered phases, indicates a sensitivity of the band gap to the degree of configurational disorder in B4C.

  • 302.
    Ektarawong, Annop
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Wang, Fei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Max Planck Institute Eisenforsch GmbH, Germany.
    Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics2016Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, nr 13, artikel-id 134503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The elastic properties of alloys between boron suboxide (B6O) and boron carbide (B13C2), denoted by (B6O)1−x(B13C2)x, as well as boron carbide with variable carbon content, ranging from B13C2 to B4C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B6O)1−x(B13C2)x is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic properties calculations demonstrate that configurational  disorder in B13C2, where a part of the C atoms in the CBC chains substitute for B atoms in the B12 icosahedra, drastically increase the Young’s and shear modulus, as compared to an atomically ordered state, B12(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B4C to B13C2. The elastic moduli of the (B6O)1−x(B13C2)x system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B6O)1−x(B13C2)x. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B6O-rich as well as ordered or disordered B13C2-rich domains in the material prepared through equilibrium routes is predicted.

  • 303.
    Eleonora Bove, Livia
    et al.
    University of Paris 06, France; Ecole Polytech Federal Lausanne, Switzerland.
    Gaal, Richard
    Ecole Polytech Federal Lausanne, Switzerland.
    Raza, Zamaan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. University of Paris 06, France.
    Ludl, Adriaan-Alexander
    University of Paris 06, France.
    Klotz, Stefan
    University of Paris 06, France.
    Marco Saitta, Antonino
    University of Paris 06, France.
    Goncharov, Alexander F.
    Carnegie Institute Science, DC 20015 USA.
    Gillet, Philippe
    Ecole Polytech Federal Lausanne, Switzerland.
    Effect of salt on the H-bond symmetrization in ice2015Ingår i: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 112, nr 27, s. 8216-8220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The richness of the phase diagram of water reduces drastically at very high pressures where only two molecular phases, proton-disordered ice VII and proton-ordered ice VIII, are known. Both phases transform to the centered hydrogen bond atomic phase ice X above about 60 GPa, i.e., at pressures experienced in the interior of large ice bodies in the universe, such as Saturn and Neptune, where nonmolecular ice is thought to be the most abundant phase of water. In this work, we investigate, by Raman spectroscopy up to megabar pressures and ab initio simulations, how the transformation of ice VII in ice X is affected by the presence of salt inclusions in the ice lattice. Considerable amounts of salt can be included in ice VII structure under pressure via rock-ice interaction at depth and processes occurring during planetary accretion. Our study reveals that the presence of salt hinders proton order and hydrogen bond symmetrization, and pushes ice VII to ice X transformation to higher and higher pressures as the concentration of salt is increased.

  • 304.
    Elevant, Jessica
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    CP-violation in Supernova Neutrino Oscillations2014Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    It is astonishing both how little and how much we know about neutrinos. On one hand, the neutrino is the second most abundant particle in our Universe. Neutrinos may be created in the Sun, core collapse supernovae, cosmic rays, geological background radiation, supernova remnants and in the Big Bang. On the other hand, they have unimaginably small masses and are unwilling to react with their surroundings. Because of their abundance and their inclination to show us physics beyond the standard model of particle physics, neutrinos are hoped to carry yet unknown information of the Universe. However, it will take some effort and time to persuade the neutrinos to tell us what they know.

    Among the things we do not yet know of the neutrinos, is the -phase in the neutrino mixing matrix. If is in fact non-zero, neutrino flavour oscillations violate CP-symmetry. Also, if neutrino masses are introduced in the standard model through the See-Saw mechanism and if leptogenesis is a valid theory, CP-violation in neutrino oscillations could help explain why our Universe has no antimatter even though equal amounts of matter and antimatter should have been created at the Big Bang.

    In this thesis, we investigate the flavour evolution of supernova neutrinos. We present the full Hamiltonian in the flavour basis for our system and identify how the different contributions affect the evolution and in which environment. We also present a theoretical motivation from [1, 2] as to how a non-zero -phase affects the flavour evolution and the final energy spectra. The analytical conclusion is that it has no impact under the assumptions made in our analysis. Thus, the -phase may not be measurable from supernova neutrinos.

  • 305.
    Eliasson, B.
    et al.
    Department of Physics Umeå University.
    Stenflo, Lennart
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Full-scale simulation study of the initial stage of ionospheric turbulence2008Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, nr 0148-0227, s. A02305-1-A02305-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a full-scale simulation of the nonlinear interaction between an intense electromagnetic wave and the Earth's ionosphere, by means of a generalized Zakharov model. The radio wave propagates from the neutral atmosphere into the ionospheric plasma layer and reaches the turning points of the ordinary and extraordinary wave modes. At the turning point of the ordinary mode, a parametric instability takes place in which the electromagnetic wave decays into an electron plasma wave and an ion acoustic wave with a typical wavelength of one meter. This is followed by collapse and caviton formation and trapping of the intense electron plasma wave. The cavitons lead to an efficient excitation of slow X (or Z) waves that propagate further into the denser ionospheric layer at higher altitudes. We use a realistic ion (oxygen) mass, length scales, and other plasma parameters. This numerical study should be useful for understanding the nonlinear interaction between intense radio waves and the ionosphere.   

  • 306.
    Eliasson, B.
    et al.
    University of Strathclyde, Scotland .
    Stenflo, Lennart
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Bingham, R.
    Rutherford Appleton Lab, England .
    Mendonca, J. T.
    Institute Super Tecn, Portugal .
    Biographical-Item: Preface in JOURNAL OF PLASMA PHYSICS, vol 79, issue , pp 981-9812013Övrigt (Övrigt vetenskapligt)
    Abstract [en]

    n/a

  • 307.
    Eliasson, B
    et al.
    University of Strathclyde, Glasgow, UK.
    Stenflo, Lennart
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Bingham, R
    Rutherford Appleton Laboratory, Didcot, UK.
    Mendonca, J T
    Institute Superior Tecnico, Lisboa, Portugal.
    Preface to special issue2013Ingår i: Journal of Plasma Physics, ISSN 0022-3778, E-ISSN 1469-7807, Vol. 79, nr 6, s. 981-981Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    This special issue is devoted to the memory of Professor Padma Kant Shukla, who passed away 26 January 2013 on his travel to New Delhi, India to receive the prestigious Hind Rattan (Jewel of India) award. Padma was born in Tulapur, Uttar Pradesh, India, 7 July 1950, where he grew up and got his education. He received a PhD degree in Physics at the Banaras Hindu University, Varanasi, Uttar Pradesh, India, in 1972, under the supervision of late Prof. R. N. Singh, and a second PhD degree in Theoretical Plasma Physics from Umeå University in Sweden in 1975, under the supervision of Prof. Lennart Stenflo. He worked at the Faculty of Physics & Astronomy, Ruhr-University Bochum, Germany since January 1973, where he was a permanent faculty member and Professor of International Affairs, a position that was created for him to honour his international accomplishments and reputation.

  • 308.
    Eliasson, Bengt
    et al.
    Ruhr University Bochum.
    Stenflo, Lennart
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Full-scale simulation study of stimulated electromagnetic emissions: The first ten milliseconds2010Ingår i: JOURNAL OF PLASMA PHYSICS, ISSN 0022-3778, Vol. 76, s. 369-375Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A full-scale numerical study is performed of the nonlinear interaction between a large-amplitude electromagnetic wave and the Earths ionosphere; and of the stimulated electromagnetic emission emerging from the turbulent layer, during the first 10 milliseconds after switch-on of the radio transmitter. The frequency spectra are downshifted in frequency and appear to emerge from a region somewhat below the cutoff of the O mode, which is characterized by Langmuir wave turbulence and localized Langmuir envelopes trapped in ion density cavities. The spectral features of escaping O-mode waves are very similar to those observed in experiments. The frequency components of Z-mode waves, trapped in the region between the O- and Z-mode cutoffs show strongly asymmetric and downshifted spectra.

  • 309.
    Elofsson, Viktor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Magnfält, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Sarakinos, Kostas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska högskolan.
    Unravelling the Physical Mechanisms that Determine Microstructural Evolution of Ultrathin Volmer-Weber Films2014Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 116, nr 4, s. 044302-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The initial formation stages (i.e., island nucleation, island growth, and island coalescence) set characteristic length scales during growth of thin films from the vapour phase. They are, thus, decisive for morphological and microstructural features of films and nanostructures. Each of the initial formation stages has previously been well-investigated separately for the case of Volmer-Weber growth, but knowledge on how and to what extent each stage individually and all together affect the microstructural evolution is still lacking. Here we address this question using growth of Ag on SiO2 from pulsed vapour fluxes as a case study. By combining in situ growth monitoring, ex situ imaging and growth simulations we systematically study the growth evolution all the way from nucleation to formation of a continuous film and establish the effect of the vapour flux time domain on the scaling behaviour of characteristic growth transitions (elongation transition, percolation and continuous film formation). Our data reveal a pulsing frequency dependence for the characteristic film growth transitions, where the nominal transition thickness decreases with increasing pulsing frequency up to a certain value after which a steady-state behaviour is observed. The scaling behaviour is shown to result from differences in island sizes and densities, as dictated by the initial film formation stages. These differences are determined solely by the interplay between the characteristics of the vapour flux and time required for island coalescence to be completed. In particular, our data provide evidence that the steady-state scaling regime of the characteristic growth transitions is caused by island growth that hinders coalescence from being completed, leading to a coalescence-free growth regime.

  • 310.
    Eriksson, Peter
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Tal, Alexey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Skallberg, Andreas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Brommesson, Caroline
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Hu, Zhang-Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Olovsson, Weine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Fairley, Neal
    Casa Software Ltd, Bay House, Teignmouth, United Kingdom.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Materials Modeling and Development Laboratory, National University of Science and Technology “MISIS”, Moscow, Russia.
    Zhang, Xuanjun
    Faculty of Health Sciences, University of Macau, Macau, SAR, China.
    Uvdal, Kajsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Cerium oxide nanoparticles with antioxidant capabilities and gadolinium integration for MRI contrast enhancement2018Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, artikel-id 6999Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The chelating gadolinium-complex is routinely used as magnetic resonance imaging (MRI) -contrast enhancer. However, several safety issues have recently been reported by FDA and PRAC. There is an urgent need for the next generation of safer MRI-contrast enhancers, with improved local contrast and targeting capabilities. Cerium oxide nanoparticles (CeNPs) are designed with fractions of up to 50% gadolinium to utilize the superior MRI-contrast properties of gadolinium. CeNPs are well-tolerated in vivo and have redox properties making them suitable for biomedical applications, for example scavenging purposes on the tissue-and cellular level and during tumor treatment to reduce in vivo inflammatory processes. Our near edge X-ray absorption fine structure (NEXAFS) studies show that implementation of gadolinium changes the initial co-existence of oxidation states Ce3+ and Ce4+ of cerium, thereby affecting the scavenging properties of the nanoparticles. Based on ab initio electronic structure calculations, we describe the most prominent spectral features for the respective oxidation states. The as-prepared gadolinium-implemented CeNPs are 3-5 nm in size, have r(1)-relaxivities between 7-13 mM(-1) s(-1) and show clear antioxidative properties, all of which means they are promising theranostic agents for use in future biomedical applications.

  • 311.
    Faber, Felix
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Characterization of attractors in a model for boundary-driven nonlinear optical waveguide arrays with disorder, gain and damping2013Självständigt arbete på grundnivå (kandidatexamen), 10,5 poäng / 16 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of this thesis is to study the effects of gain and damping on a nonlinear waveguide array with a strong disorder that is driven in the first site, and try to find regimes which have stable stationary solutions. This has been done with a modified DNLS (Discrete nonlinear Schrödinger equation). Stable stationary solutions were mainly found when the damping was stronger than the gain, but some stable stationary regimes were also found when the gain was stronger than the damping.

  • 312.
    Faber, Felix A.
    et al.
    Department of Chemistry, University of Basel, Switzerland.
    Lindmaa, Alexander
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    von Lilienfeld, O. Anatole
    Department of Chemistry, University of Basel, Switzerland.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Machine Learning Energies of 2 Million Elpasolite (AB2D6) Crystals2016Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, ISSN 031-9007, Vol. 117, nr 13, artikel-id 135502Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elpasolite is the predominant quaternary crystal structure (AlNaK2F6 prototype) reported in the Inorganic Crystal Structure Database. We develop a machine learning model to calculate density functional theory quality formation energies of all ∼2×106 pristine ABC2D6 elpasolite crystals that can be made up from main-group elements (up to bismuth). Our model’s accuracy can be improved systematically, reaching a mean absolute error of 0.1  eV/atom for a training set consisting of 10×103 crystals. Important bonding trends are revealed: fluoride is best suited to fit the coordination of the D site, which lowers the formation energy whereas the opposite is found for carbon. The bonding contribution of the elements A and B is very small on average. Low formation energies result from A and B being late elements from group II, C being a late (group I) element, and D being fluoride. Out of 2×106 crystals, 90 unique structures are predicted to be on the convex hull—among which is NFAl2Ca6, with a peculiar stoichiometry and a negative atomic oxidation state for Al.

  • 313.
    Faber, Felix
    et al.
    University of Basel, Switzerland; University of Basel, Switzerland; University of Basel, Switzerland.
    Lindmaa, Alexander
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    von Lilienfeld, O. Anatole
    University of Basel, Switzerland; Argonne Leadership Comp Facil, IL 60439 USA; Argonne National Lab, IL 60439 USA.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Crystal structure representations for machine learning models of formation energies2015Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 115, nr 16, s. 1094-1101Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We introduce and evaluate a set of feature vector representations of crystal structures for machine learning (ML) models of formation energies of solids. ML models of atomization energies of organic molecules have been successful using a Coulomb matrix representation of the molecule. We consider three ways to generalize such representations to periodic systems: (i) a matrix where each element is related to the Ewald sum of the electrostatic interaction between two different atoms in the unit cell repeated over the lattice; (ii) an extended Coulomb-like matrix that takes into account a number of neighboring unit cells; and (iii) an ansatz that mimics the periodicity and the basic features of the elements in the Ewald sum matrix using a sine function of the crystal coordinates of the atoms. The representations are compared for a Laplacian kernel with Manhattan norm, trained to reproduce formation energies using a dataset of 3938 crystal structures obtained from the Materials Project. For training sets consisting of 3000 crystals, the generalization error in predicting formation energies of new structures corresponds to (i) 0.49, (ii) 0.64, and (iii) 0.37eV/atom for the respective representations.

  • 314.
    Fahlgren, Anna
    et al.
    Linköpings universitet, Institutionen för klinisk och experimentell medicin, Ortopedi. Linköpings universitet, Hälsouniversitetet.
    Yang, Xu
    Hospital for Special Surgery, New York, USA.
    Ciani, Cesare
    Hospital for Special Surgery, New York, USA.
    Ryan, James A.
    Hospital for Special Surgery, New York, USA.
    Kelly, Natalie
    Hospital for Special Surgery, New York, USA.
    Ko, Frank C.
    Cornell University, Ithaca, USA.
    van der Meulen, Marjolein C. H.
    Hospital for Special Surgery, New York, USA.
    Boström, Mathias P. G.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    The effects of PTH, loading and surgical insult on cancellous bone at the bone-implant interface in the rabbit2013Ingår i: Bone, ISSN 8756-3282, E-ISSN 1873-2763, Vol. 52, nr 2, s. 718-724Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Enhancing the quantity and quality of cancellous bone with anabolic pharmacologic agents may lead to more successful outcomes of non-cemented joint replacements. Using a novel rabbit model of cancellous bone loading, we examined two specific questions regarding bone formation at the bone-implant interface: (1) does the administration of intermittent PTH, a potent anabolic agent, and mechanical loading individually and combined enhance the pen-implant cancellous bone volume fraction; and, (2) does surgical trauma enhance the anabolic effect of PTH on pen-implant bone volume fraction. In this model, PTH enhanced pen-implant bone volume fraction by 30% in loaded bone, while mechanical loading alone increased bone volume fraction modestly (+10%). Combined mechanical loading and PTH treatment had no synergistic effect on any cancellous parameters. However, a strong combined effect was found in bone volume fraction with combined surgery and PTH treatment (+34%) compared to intact control limbs. Adaptive changes in the cancellous bone tissue included increased ultimate stress and enhanced remodeling activity. The number of proliferative osteoblasts increased as did their expression of pro-collagen 1 and PTH receptor 1, and the number of TRAP positive osteoclasts also increased. In summary, both loading and intermittent PTH treatment enhanced pen-implant bone volume, and surgery and PTH treatment had a strong combined effect This finding is of clinical importance since enhancing early osseointegration in the post-surgical period has numerous potential benefits.

  • 315.
    Falk, Abram L.
    et al.
    University of Chicago, IL 60637 USA University of Calif Santa Barbara, CA 93106 USA .
    Klimov, Paul V.
    University of Chicago, IL 60637 USA University of Calif Santa Barbara, CA 93106 USA .
    Buckley, Bob B.
    University of Calif Santa Barbara, CA 93106 USA .
    Ivády, Viktor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Calusine, Greg
    University of Calif Santa Barbara, CA 93106 USA .
    Koehl, William F.
    University of Chicago, IL 60637 USA University of Calif Santa Barbara, CA 93106 USA .
    Gali, Adam
    Hungarian Academic Science, Hungary Budapest University of Technology and Econ, Hungary .
    Awschalom, David D.
    University of Chicago, IL 60637 USA University of Calif Santa Barbara, CA 93106 USA .
    Electrically and Mechanically Tunable Electron Spins in Silicon Carbide Color Centers2014Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, nr 18, s. 187601-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electron spins of semiconductor defects can have complex interactions with their host, particularly in polar materials like SiC where electrical and mechanical variables are intertwined. By combining pulsed spin resonance with ab initio simulations, we show that spin-spin interactions in 4H-SiC neutral divacancies give rise to spin states with a strong Stark effect, sub-10(-6) strain sensitivity, and highly spin-dependent photoluminescence with intensity contrasts of 15%-36%. These results establish SiC color centers as compelling systems for sensing nanoscale electric and strain fields.

  • 316.
    Falk, Abram L.
    et al.
    University of Chicago, IL 60637 USA; IBM TJ Watson Research Centre, NY 10598 USA.
    Klimov, Paul V.
    University of Chicago, IL 60637 USA; University of Calif Santa Barbara, CA 93106 USA; Hungarian Academic Science, Hungary.
    Ivády, Viktor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary.
    Szasz, Krisztian
    Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary; Eotvos Lorand University, Hungary.
    Christle, David J.
    University of Chicago, IL 60637 USA; University of Calif Santa Barbara, CA 93106 USA; Hungarian Academic Science, Hungary.
    Koehl, William F.
    University of Chicago, IL 60637 USA.
    Gali, Adam
    Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Hungary; Budapest University of Technology and Econ, Hungary.
    Awschalom, David D.
    University of Chicago, IL 60637 USA.
    Optical Polarization of Nuclear Spins in Silicon Carbide2015Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, nr 24, s. 247603-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We demonstrate optically pumped dynamic nuclear polarization of Si-29 nuclear spins that are strongly coupled to paramagnetic color centers in 4H- and 6H-SiC. The 99% +/- 1% degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5 mu K. By combining ab initio theory with the experimental identification of the color centers optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging.

  • 317.
    Fallqvist, Amie
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska fakulteten.
    Olovsson, Weine
    Linköpings universitet, Nationellt superdatorcentrum (NSC). Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Max Planck Inst Eisenforsch GmbH, Germany.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Belov, M. P.
    Natl Univ Sci and Technol MISIS, Russia.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Resolving the debated atomic structure of the metastable cubic SiNx tissue phase in nanocomposites with TiN2018Ingår i: Physical Review Materials, ISSN 2475-9953, Vol. 2, nr 9, artikel-id 093608Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The TiN/SiNx nanocomposite and nanolaminate systems are the archetype for super if not ultrahard materials. Yet, the nature of the SiNx tissue phase is debated. Here, we show by atomically resolved electron microscopy methods that SiNx is epitaxially stabilized in a NaCl structure on the adjacent TiN(001) surfaces. Additionally, electron energy loss spectroscopy, supported by first-principles density functional theory calculations infer that SiNx hosts Si vacancies.

  • 318.
    Fallqvist, Amie
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Olovsson, Weine
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Evidence for B1-cubic SiNx by Aberration-Corrected Analytical STEMManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The crystal structure of epitaxially stabilized SiNx layers on TiN(001) was investigated by analytical aberration corrected electron microscopy. Atomically resolved images of the structure, which were acquired by scanning transmission electron microscopy using high angle annular dark field and annular bright field detectors, are used to identify the B1-cubic structure of SiNx. To corroborate the acquired images, image simulations were performed using candidate structures. Complementary to imaging, spatially resolved electron energy loss spectroscopy of the epitaxial SiNx layers was performed to acquire the symmetry specific nitrogen near edge fine-structure. Finally, full potential calculations performed to determine the near edge structure from candidate crystal structures confirms the existence of B1-cubic SiNx.

  • 319.
    Fashandi, Hossein
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dahlqvist, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Andersson, Mike
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC2017Ingår i: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 16, nr 8, s. 814-818Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si. Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 degrees C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.

  • 320.
    Fashandi, Hossein
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska högskolan.
    Ivády, Viktor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan. Wigner Research Centre for Physics, Hungarian Academy of Sciences, Budapest, Hungary.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad sensorvetenskap. Linköpings universitet, Tekniska högskolan.
    Katsnelson, Mikhail I.
    Radboud University of Nijmegen, Institute for Molecules and Materials, Nijmegen, The Netherlands / Dept. of Theoretical Physics and Applied Mathematics, Ural Federal University, Russia.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan. School of Information and Communication Technology, KTH, Stockholm, Sweden.
    Dirac points with giant spin-orbit splitting in the electronic structure of two-dimensional transition-metal carbides2015Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, nr 15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We investigated the structural and electrical properties of 2D MXene sheets by means of firstprinciples density functional theory (DFT) calculations. To describe the Kohn-Sham states, plane wave basis set and projector augmented wave method (PAW) were used as implemented in the Vienna ab initio Simulation Package (VASP). We applied PBE parameterization of the generalized gradient approximation of the exchange and correlation energy functional to account for many-body effects of the interacting electron system. Convergent sampling of the Brillouin-zone was achieved by a Γ-centered 15×15×1 grid. In order to model a single sheet of MXene we ensured at least 30 Å vacuum between the periodically repeated sheets. For the structural optimization 1×10−3 eV/Å force criteria was used. The relativistic spin-orbit coupling effects were also included in our simulations regarding band structure and density of states.

  • 321.
    Feng, Qingguo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Jönsson, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. NUST MISIS, Russia.
    Topological transitions of the Fermi surface of osmium under pressure: an LDA plus DMFT study2017Ingår i: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 19, artikel-id 033020Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of pressure on the electronic structure of Os has attracted substantial attention recently due to reports on isostructural electronic transitions in this metal. Here, we theoretically investigate the Fermi surface of Os from ambient to high pressure, using density functional theory combined with dynamical mean field theory. Weprovide a detailed discussion of the calculated Fermi surface and its dependence on the level of theory used for the treatment of the electron-electron interactions. Although we confirm that Os can be classified as weakly correlated metal, the inclusion of local quantum fluctuations between 5d electrons beyond the local density approximation explains the most recent experimental reports regarding the occurrence of electronic topological transitions in Os.

  • 322.
    Fernandez, J.R.L.
    et al.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Moyses, Araujo C.
    Moysés Araújo, C., Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    Ferreira, Da Silva A.
    Ferreira Da Silva, A., Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    Leite, J.R.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Tabata, A.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Abramof, E.
    Instituto Nacional De Pesquisas Espaciais (INPE-LAS), CP 515, 12201-970 Sao Jose dos Campos, SP, Brazil.
    Chitta, V.A.
    Instituto De Física, Universidade De São Paulo, CP66318, 05315-970 São Paulo, SP, Brazil.
    Persson, C.
    Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Ahuja, R.
    Department of Physics, Uppsala University, SE-751 21 Uppsala, Sweden.
    Pepe, I.
    Instituto De Física, Universidade Federal Da Bahia, Campus Universitário De Ondina, 40210-340 Salvador, Bahia, Brazil.
    As, D.J.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Frey, T.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Schikora, D.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Lischka, K.
    Universität Paderborn, FB-6 Physik, D-33095 Paderborn, Germany.
    Electrical resistivity and band-gap shift of Si-doped GaN and metal-nonmetal transition in cubic GaN, InN and AlN systems2001Ingår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 231, nr 3, s. 420-427Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The critical impurity concentration Nc of the metal-nonmetal (MNM) transition for the cubic GaN, InN and AlN systems, is calculated using the following two different criteria: vanishing of the donor binding energy and the crossing point between the energies in the metallic and insulating phases. A dielectric function model with a Lorentz-Lorenz correction is used for the insulating phase. The InN presents an order of magnitude increase in Nc as compared to the other two systems. The electrical resistivity of the Si-donor system GaN is investigated theoretically and experimentally from room temperature down to 10 K. It presents a metallic character above a certain high impurity concentration identified as Nc. The samples were grown by plasma assisted molecular beam epitaxy (MBE) on GaAs (0 0 1) substrate. The model calculation is carried out from a recently proposed generalized Drude approach (GDA) presenting a very good estimation for the metallic region. The band-gap shift (BGS) of Si-doped GaN has also been investigated above the MNM transition where this shift is observed. Theoretical and experimental results have a rough agreement in a range of impurity concentration of interest. © 2001 Elsevier Science B.V. All rights reserved.

  • 323.
    Ferrari, Alberto
    et al.
    Ruhr Univ Bochum, Germany.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Ruhr Univ Bochum, Germany.
    Rogal, Jutta
    Ruhr Univ Bochum, Germany.
    Drautz, Ralf
    Ruhr Univ Bochum, Germany.
    First-principles characterization of reversible martensitic transformations2019Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 99, nr 9, artikel-id 094107Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Reversible martensitic transformations (MTs) are the origin of many fascinating phenomena, including the famous shape memory effect. In this work, we present a fully ab initio procedure to characterize MTs in alloys and to assess their reversibility. Specifically, we employ ab initio molecular dynamics data to parametrize a Landau expansion for the free energy of the MT. This analytical expansion makes it possible to determine the stability of the high- and low-temperature phases, to obtain the Ehrenfest order of the MT, and to quantify its free energy barrier and latent heat. We apply our model to the high-temperature shape memory alloy Ti-Ta, for which we observe remarkably small values for the metastability region (the interval of temperatures in which the high-and low-temperature phases are metastable) and for the barrier: these small values are necessary conditions for the reversibility of MTs and distinguish shape memory alloys from other materials.

  • 324.
    Ferreira, da Silva A.
    et al.
    Ferreira da Silva, A., Instituto de Física, Lab. de Propriedades Óticas, Camp. Universitário de Ondina, 40210-340 Salvador, Bahia, Brazil.
    Pepe, I.
    Instituto de Física, Lab. de Propriedades Óticas, Camp. Universitário de Ondina, 40210-340 Salvador, Bahia, Brazil.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Persson, C.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-75121 Uppsala, Sweden, National Renewable Energy Laboratory, Golden, CO 80401.
    Ahuja, R.
    Condensed Matter Theory Group, Department of Physics, Uppsala University, SE-75121 Uppsala, Sweden.
    De, Souza J.P.
    De Souza, J.P., Institute de Física, Univ. Federal do Rio Grande do Sul, 91501970 Porto Alegre, RS, Brazil, Thomas J. Watson Research Center, IBM, Yorktown Heights, NY 10598.
    Suzuki, Y.
    Physics Department, City College, City University of New York, New York 10031.
    Yang, Y.
    Physics Department, City College, City University of New York, New York 10031.
    Electrical resistivity of acceptor carbon in GaAs2004Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 95, nr 5, s. 2532-2535Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The resistivity of GaAs implanted with carbon acceptors for concentrations spanning the insulating to the metallic regimes were investigated experimentally and theoretically between room temperature and 1.7 K. The resistivities obtained experimentally were compared with resistivity values calculated from a generalized Drude approach. The value of the critical impurity concentration was found to be about 1018cm-3. Good agreement was obtained between the experimental results and calculations.

  • 325.
    Ferreira, Da Silva A.
    et al.
    Ferreira Da Silva, A., Instituto de Fisica, Universidade Federal da Bahia, Campus Ondina, 40210-340 Salvador, BA, Brazil.
    Pernot, J.
    Laboratoire d'Etudes des Propriétés Electroniques des Solides (CNRS), 25 avenue des Martyrs, 38042 Grenoble Cedex 9, France, Université Joseph Fourier, BP 53, 38041 Grenoble Cedex 9, France.
    Contreras, S.
    Groupe d'Etude des Semiconducteurs, UM2-CNRS (UMR 5650), cc074, 34095 Montpellier, Cedex 5, France.
    Sernelius, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Persson, C.
    Department of Materials Science and Engineering, Royal Institute of Technology, SE-100 44 Stockholm, Sweden.
    Camassel, J.
    Groupe d'Etude des Semiconducteurs, UM2-CNRS (UMR 5650), cc074, 34095 Montpellier, Cedex 5, France.
    Electrical resistivity and metal-nonmetal transition in n -type doped 4H-SiC2006Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 74, nr 24, s. 245201-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electrical resistivity of 4H-SiC doped with nitrogen is analyzed in the temperature range 10- 700 K for nitrogen concentrations between 3.5× 1015 and 5× 1019 cm-3. For the highest doped samples, a good agreement is found between the experimental resistivity and the values calculated from a generalized Drude approach at similar dopant concentration and temperature. From these results, the critical concentration (Nc) of nitrogen impurities which corresponds to the metal-nonmetal transition in 4H-SiC is deduced. We find Nc ~ 1019 cm-3. © 2006 The American Physical Society.

  • 326.
    Ferreira da Silva, Antonio
    et al.
    University of Federal Bahia, Brazil.
    Levine, Alexandre
    University of Sao Paulo, Brazil.
    Sadre Momtaz, Zahra
    University of Sao Paulo, Brazil.
    Boudinov, Henri
    University of Federal Rio Grande do Sul, Brazil.
    Sernelius, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Magnetoresistance of doped silicon2015Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, nr 21, s. 214414-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have performed longitudinal magnetoresistance measurements on heavily n-doped silicon for donor concentrations exceeding the critical value for the metal-nonmetal transition. The results are compared to those from a many-body theory where the donor electrons are assumed to reside at the bottom of the many-valley conduction band of the host. Good qualitative agreement between theory and experiment is obtained.

  • 327.
    Filippov, Stanislav
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    Grinderslev, Jakob B.
    Aarhus Univ, Denmark.
    Andersson, Mikael S.
    Chalmers Univ Technol, Sweden.
    Armstrong, Jeff
    Rutherford Appleton Lab, England.
    Karlsson, Maths
    Chalmers Univ Technol, Sweden.
    Jensen, Torben R.
    Aarhus Univ, Denmark.
    Klarbring, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Haussermann, Ulrich
    Stockholm Univ, Sweden.
    Analysis of Dihydrogen Bonding in Ammonium Borohydride2019Ingår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, nr 47, s. 28631-28639Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structural and vibrational properties of ammonium borohydride, NH4BH4, have been examined by first-principles density functional theory (DFT) calculations and inelastic neutron scattering (INS). The H disordered crystal structure of NH4BH4 is composed of the tetrahedral complex ions NH4+ and BH4-, which are arranged as in the fcc NaCl structure and linked by intermolecular dihydrogen bonding. Upon cooling, the INS spectra revealed a structural transition between 45 and 40 K. The reversible transition occurs upon heating between 46 and 49 K. In the low-temperature form reorientational dynamics are frozen. The libration modes for BH4- and NH4+ are near 300 and 200 cm(-1), respectively. Upon entering the fcc high-temperature form, NH4+ ions attain fast reorientational dynamics, as indicated in the disappearance of the NH4+ libration band, whereas BH4- ions become significantly mobile only at temperatures above 100 K. The vibrational behavior of BH4- ions in NH4BH4 compares well to the heavier alkali metal borohydrides, NaBH4-CsBH4. DFT calculations revealed a nondirectional nature of the dihydrogen bonding in NH4BH4 with only weak tendency for long-range order. Different rotational configurations of complex ions appear quasi-degenerate, which is reminiscent of glasses.

  • 328.
    Filippov, Stanislav
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    Klarbring, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Haussermann, Ulrich
    Stockholm Univ, Sweden.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Temperature-induced phase transition and Li self-diffusion in Li2C2: A first-principles study2019Ingår i: PHYSICAL REVIEW MATERIALS, ISSN 2475-9953, Vol. 3, nr 2, artikel-id 023602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lithium carbide, Li2C2, is a fascinating material that combines strong covalent and weak ionic bonding resulting in a wide range of unusual properties. The mechanism of its phase transition from the ground-state orthorhombic (Immm) to the high-temperature cubic (Fm (3) over barm) crystal structure is not well understood and here we elucidate it with help of first-principles calculations. We show that stabilization of the cubic phase is a result of a temperature-induced disorientation of the C-C dumbbells and their further thermal rotations. Due to these rotations rather large deviatoric stress, which is associated with the dumbbell alignment along one of the crystallographic axes, averages out making the cubic structure mechanically stable. At high temperature we observe a type-II superionic transition to a state of high Li self-diffusion involving collective ionic motion mediated by the formation of Frenkel pairs.

  • 329.
    Finzel, Kati
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    About the atomic shell structure in real space and the Pauli exclusion principle2016Ingår i: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 135, nr 6, s. 148-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown that any set of eigenfunctions (1s, 2s) of a bare Coulomb Hamiltonian exhibit the same atomic shell structure pattern for the real-space indicator a(1), which is defined as the ratio between the positive kinetic energy density and the electron density. Since this model Hamiltonian excludes all effects due to the electron-electron repulsion, the appearance of the atomic shell structure is attributed to the Pauli exclusion principle that arises from the requirements for a fermionic wavefunction. Since the derivation is independent of the nuclear charge and the energy of the system, reversely imposing proper atomic shell structure behavior in the design of kinetic energy functionals mimics the Pauli exclusion principle during a variational process.

  • 330.
    Finzel, Kati
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    About the compatibility between ansatzes and constraints for a local formulation of orbital-free density functional theory2017Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 117, nr 5, artikel-id UNSP e25329Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Functional properties that are exact for the Hohenberg-Kohn functional may turn into mutually exclusive constraints at a given level of ansatz. This is exemplarily shown for the local density approximation. Nevertheless, it is possible to reach exactly the Kohn-Sham data from an orbital-free density functional framework based on simple one-point functionals by starting from the Levy-Perdew-Sahni formulation. The energy value is obtained from the density-potential pair, and therefore does not refer to the functional dependence of the potential expression. Consequently, the potential expression can be obtained from any suitable model and is not required to follow proper scaling behavior.

  • 331.
    Finzel, Kati
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    About the Difference Between Density Functionals Defined by Energy Criterion and Density Functionals Defined by Density Criterion: Exchange Functionals2016Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 116, nr 15, s. 1187-1189Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The difference between density functionals defined by energy criterion and density functionals defined by density criterion is studied for the exchange functional. It is shown that Slater potentials are exact exchange potentials in the sense that they yield the Hartree-Fock electron density if all operators are given by local expressions. (C) 2016 Wiley Periodicals, Inc.

  • 332.
    Finzel, Kati
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Approximating the Pauli Potential in Bound Coulomb Systems2016Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 116, nr 16, s. 1261-1266Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown that the Pauli potential in bound Coulomb systems can in good approximation be composed from the corresponding atomic fragments. This provides a simple and fast procedure how to generate the Pauli potential in bound systems, which is needed to perform an orbital-free density functional calculation. The method is applicable to molecules and solids. (c) 2016 Wiley Periodicals, Inc.

  • 333.
    Finzel, Kati
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Reinvestigation of the ideal atomic shell structure and its application in orbital-free density functional theory2016Ingår i: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 135, nr 4, s. 87-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It is shown how to determine the ideal shell radii solely as a function of the nuclear charge. With the help of those ideal shell radii, an approximation to the Pauli potential for atoms in their groundstate can be constructed. The so-called SSB-ideal potential (shell structure-based) yields self-consistent orbital-free electron densities with proper atomic shell structure from Hohenberg-Kohn variational principle.

  • 334.
    Finzel, Kati
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ayers, Paul W.
    McMaster University, Canada.
    Functional constructions with specified functional derivatives2016Ingår i: Theoretical Chemistry accounts, ISSN 1432-881X, E-ISSN 1432-2234, Vol. 135, nr 12, artikel-id 255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A bifunctional construction depending on a specified density-potential pair and an approximate guiding electron density functional is presented. The proposed bifunctional construction properly transforms under homogeneous coordinate scaling and yields the specified functional derivative, which determines the electron density. Whereas the method is general and applicable to all functional types, it will prove especially helpful in the context of orbital-free density functional theory, where most existing approximate density functionals predict inaccurate potentials.

  • 335.
    Finzel, Kati
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Baranov, Alexey I.
    Max Planck Institute Chemistry Phys Solids, Germany.
    A simple model for the Slater exchange potential and its performance for solids2017Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 117, nr 1, s. 40-47Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A simple local model for the Slater exchange potential is determined by least square fit procedure from Hartree-Fock (HF) atomic data. Since the Slater potential is the exact exchange potential yielding HF electron density from Levy-Perdew-Sahni density functional formalism (Levy et al., Phys. Rev. A 1984, 30, 2745), the derived local potential is significantly more negative than the conventional local density approximation. On the set of 22 ionic, covalent and van der Waals solids including strongly correlated transition metal oxides, it has been demonstrated, that this simple model potential is capable of reproducing the band gaps nearly as good as popular meta GGA potentials in close agreement with experimental values.

  • 336.
    Finzel, Kati
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Davidsson, Joel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Energy-Surfaces from the Upper Bound of the Pauli Kinetic Energy2016Ingår i: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 116, nr 18, s. 1337-1341Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on the Kohn-Sham Pauli potential and the Kohn-Sham electron density, the upper bound of the Pauli kinetic energy is tested as a suitable replacement for the exact Pauli kinetic energy for application in orbital-free density functional calculations. It is found that bond lengths for strong and moderately bound systems can be qualitatively predicted, but with a systematic shift toward larger bond distances with a relative error of 6% up to 30%. Angular dependence of the energy-surface cannot be modeled with the proposed functional. Therefore, the upper bound model is the first parameter-free functional expression for the kinetic energy that is able to qualitatively reproduce binding curves with respect to bond distortions. (C) 2016 Wiley Periodicals, Inc.

  • 337.
    Flink, Axel
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Andersson, J.M.
    Seco Tools AB.
    Alling, Björn
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Daniel, R.
    Christian Doppler Laboratory for Advanced Hard Coatings.
    Sjölén, J.
    Seco Tools AB.
    Karlsson, L.
    Seco Tools AB.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Structure and thermal stability of arc evaporated (Ti0.33Al0.67)1 − xSixN thin films2008Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 517, nr 2, s. 714-721Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    (Ti0.33Al0.67)1 − xSixN (0 ≤ x ≤ 0.29) thin solid films were deposited onto cemented carbide substrates by arc evaporation and analyzed using analytical electron microscopy, X-ray diffraction, nanoindentation, and density functional theory. As-deposited films with x ≤ 0.02 consisted mainly of a metastable c-(Ti,Al)N solid solution for which Si serves as a veritable grain refiner. Additional Si promoted growth of a hexagonal wurtzite (Al,Ti,Si)N solid solution, which dominated at 0.02 < x < 0.17. For x ≥ 0.17, the films were X-ray amorphous. Despite these widely different microstructures, all as-deposited films had nanoindentation hardness in the narrow range of 22–25 GPa. Isothermal annealing of the x = 0.01 alloy film at a temperature of 900 °C, corresponding to that in turning operation, resulted in spinodal decomposition into c-AlN and TiN and precipitation of h-AlN. For x = 0.09 films, annealing between 600 °C and 1000 °C yielded c-TiN precipitation from the h-(Al,Ti,Si)N phase. Furthermore, the x = 0.01 and x = 0.09 films exhibited substantial age hardening at 900 °C, to 34 GPa and 29 GPa due to spinodal decomposition and c-TiN precipitation, respectively. Films with a majority of c-(Ti,Al)N phase worked best in steel turning tests, while films with x > 0.02 developed cracks during such operation. We propose that the cracks are due to tensile strain which is caused by a decrease in molar volume during the phase transformation from hexagonal wurtzite (Al,Ti,Si)N into cubic TiN phase, which results in degradation in machining performance.

  • 338.
    Forsén, Rikard
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Schramm, I. C.
    Functional Materials, Department Materials Science, Saarland University, Saarbrücken, Germany.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per O Å
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mücklich, F.
    Institute of Ion Beam Physics and Materials Research, Forschungszentrum Dresden-Rossendorf.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Nanostructuring and coherency strain in multicomponent hard coatings2014Ingår i: APL MATERIALS, ISSN 2166-532X, Vol. 2, nr 11, s. 116104-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Lattice resolved and quantitative compositional characterizations of the microstructure in TiCrAlN wear resistant coatings emerging at elevated temperatures are performed to address the spinodal decomposition into nanometer-sized coherent cubic TiCr- and Al-rich domains. The domains coarsen during annealing and at 1100 ºC, the Al-rich domains include a metastable cubic Al(Cr)N phase containing 9 at.% Cr and a stable hexagonal AlN phase containing less than 1 at.% Cr. The cubic and the hexagonal phases form strained semi-coherent interfaces with each other.

  • 339.
    Fritton, Massimo
    et al.
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    Otte, Katrin
    Bavarian Acad Sci and Humanities, Germany.
    Björk, Jonas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Biswas, Pronay Kumar
    Univ Siegen, Germany.
    Heckl, Wolfgang M.
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    Schmittel, Michael
    Univ Siegen, Germany.
    Lackinger, Markus
    Deutsch Museum, Germany; Tech Univ Munich, Germany.
    The influence of ortho-methyl substitution in organometallic self-assembly - a comparative study on Cu(111) vs. Ag(111)2018Ingår i: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 54, nr 70, s. 9745-9748Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Metal surface-induced dehalogenation of precursors is known to initiate self-assembly of organometallic networks, where tectons are connected via carbon-metal-carbon (C-M-C) bonds. Even though reversibility of the C-M-C bonds facilitates structural equilibration, defects associated with highly bent organometallic linkages are still commonly observed. By introducing a steric hindrance to reduce the C-M-C bond angle flexibility, we find well ordered organometallic networks of an ortho-methyl substituted 1,3,5-tris(p-bromophenyl)-benzene analogue on Cu(111) after room-temperature (RT) deposition and on Ag(111) after annealing.

  • 340.
    Fräjdin-Hellqvist, Ulla-Britt
    et al.
    Svenskt Näringsliv.
    Honeth, Peter
    Lunds universitet.
    Berggren, Karl-Fredrik
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Missa inte chansen med ESS2005Ingår i: Ny teknik, ISSN 0550-8754, nr 24Artikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 341.
    Gambino, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Structural and magnetic disorder in crystalline materials: a first principles study2019Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Disorder in crystalline materials can take different forms and originate from different sources. In particular, temperature introduces disorder in any kind of material. This can be observed as the appearance of vacant lattice sites in an otherwise perfect crystal, or as a random distribution of different elements on the same lattice in an alloy; at the same time, if the material is magnetic, temperature induces disorder also on the magnetic degrees of freedom. In this thesis, different levels of disorder associated to structure and magnetism are investigated by means of density functional theory and thermodynamic models.

    I start with diffusion of Ti vacancies in TiN, which is studied by means of nonequilibrium ab initio molecular dynamics using the color diffusion algorithm at different temperatures. The result is an Arrhenius behavior of Ti vacancy jump rates.

    A method to perform structural relaxations in magnetic materials in their hightemperature paramagnetic phase is then developed based on the disordered local moments approach in order to study vacancies, interstitial atoms, and combinations of defects in paramagnetic bcc Fe and B1 CrN, as well as the mixing enthalpy of bcc Fe1−xCrx random alloys. A correction to the energetics of every system due to the relaxation in the disordered magnetic state is observed in all cases.

    Not related to temperature and disorder, but very important for an accurate description of magnetic materials, is the choice of the exchange and correlation functional to be employed in the first principles calculations. We have investigated the performance of a recently developed meta-GGA functional, the strongly constrained and appropriately normed (SCAN) functional, in comparison with the more commonly used LDA and PBE on the ferromagnetic elemental solids bcc Fe, fcc Ni, and hcp Co, and SCAN it is found to give negligible improvements, if not a worsening, in the description of these materials.

    Finally, the coupling between vibrational and magnetic degrees of freedom is discussed by reviewing the literature and proposing an investigation of the influence of vibrations on longitudinal spin fluctuations. These excitations are here studied by means of thermodynamic models based on Landau expansion of the energy in even powers of the magnitude of the local magnetic moments. We find that vibrational and magnetic disorder alter the energy landscapes as a function of moment size also in bcc Fe, which is often considered a Heisenberg system, inducing a more itinerant electron behavior.

    Delarbeten
    1. Nonequilibrium ab initio molecular dynamics determination of Ti monovacancy migration rates in B1 TiN
    Öppna denna publikation i ny flik eller fönster >>Nonequilibrium ab initio molecular dynamics determination of Ti monovacancy migration rates in B1 TiN
    2017 (Engelska)Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, nr 10, artikel-id 104306Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    We use the color diffusion (CD) algorithm in nonequilibrium (accelerated) ab initio molecular dynamics simulations to determine Ti monovacancy jump frequencies in NaCl-structure titanium nitride (TiN), at temperatures ranging from 2200 to 3000 K. Our results showthat theCDmethod extended beyond the linear-fitting rate-versus-force regime [Sangiovanni et al., Phys. Rev. B 93, 094305 (2016)] can efficiently determine metal vacancy migration rates in TiN, despite the low mobilities of lattice defects in this type of ceramic compound. We propose a computational method based on gamma-distribution statistics, which provides unambiguous definition of nonequilibrium and equilibrium (extrapolated) vacancy jump rates with corresponding statistical uncertainties. The acceleration-factor achieved in our implementation of nonequilibrium molecular dynamics increases dramatically for decreasing temperatures from 500 for T close to the melting point T-m, up to 33 000 for T approximate to 0.7 T-m

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2017
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-141712 (URN)10.1103/PhysRevB.96.104306 (DOI)000411076000005 ()
    Anmärkning

    Funding Agencies|Swedish Foundation for Strategic Research (SSF) project SRL [10-0026]; Swedish Research Council (VR) [621-2011-4417, 2015-04391, 330-2014-6336]; Swedish Government Strategic Research Area Grant in Materials Science on Advanced Functional Materials [MatLiU 2009-00971]; Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Marie Sklodowska Curie Actions [INCA 600398]; Swedish Foundation for Strategic Research; Stiftelsen Olle Engkvist Byggmastare

    Tillgänglig från: 2017-10-05 Skapad: 2017-10-05 Senast uppdaterad: 2019-06-28
    2. Lattice relaxations in disordered Fe-based materials in the paramagnetic state from first principles
    Öppna denna publikation i ny flik eller fönster >>Lattice relaxations in disordered Fe-based materials in the paramagnetic state from first principles
    2018 (Engelska)Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, nr 6, artikel-id 064105Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    The first-principles calculation of many material properties, in particular related to defects and disorder, starts with the relaxation of the atomic positions of the system under investigation. This procedure is routine for nonmagnetic and magnetically ordered materials. However, when it comes to magnetically disordered systems, in particular the paramagnetic phase of magnetic materials, it is not clear how the relaxation procedure should be performed or which geometry should be used. Here we propose a method for the structural relaxation of magnetic materials in the paramagnetic regime, in an adiabatic fast-magnetism approximation within the disordered local moment (DLM) picture in the framework of density functional theory. The method is straightforward to implement using any ab initio code that allows for structural relaxations. We illustrate the importance of considering the disordered magnetic state during lattice relaxations by calculating formation energies and geometries for an Fe vacancy and C insterstitial atom in body-centered cubic (bcc) Fe as well as bcc Fe1-xCrx random alloys in the paramagnetic state. In the vacancy case, the nearest neighbors to the vacancy relax toward the vacancy of 0.14 angstrom (-5% of the ideal bcc nearest-neighbor distance), which is twice as large as the relaxation in the ferromagnetic case. The vacancy formation energy calculated in the DLM state on these positions is 1.60 eV, which corresponds to a reduction of about 0.1 eV compared to the formation energy calculated using DLM but on ferromagnetic-relaxed positions. The carbon interstitial formation energy is found to be 0.41 eV when the DLM relaxed positions are used, as compared to 0.59 eV when the FM-relaxed positions are employed. For bcc Fe0.5Cr0.5 alloys, the mixing enthalpy is reduced by 5 meV/atom, or about 10%, when the DLM state relaxation is considered, as compared to positions relaxed in the ferromagnetic state.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2018
    Nationell ämneskategori
    Den kondenserade materiens fysik
    Identifikatorer
    urn:nbn:se:liu:diva-151199 (URN)10.1103/PhysRevB.98.064105 (DOI)000443139600004 ()
    Anmärkning

    Funding Agencies|Swedish Research Council (VR) [2014-6336]; Marie Sklodowska Curie Actions, Cofund [INCA 600398]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFOMatLiU) [2009 00971]; Swedish Foundation for Strategic Research

    Tillgänglig från: 2018-09-13 Skapad: 2018-09-13 Senast uppdaterad: 2019-05-14
    3. Assessing the SCAN functional for itinerant electron ferromagnets
    Öppna denna publikation i ny flik eller fönster >>Assessing the SCAN functional for itinerant electron ferromagnets
    Visa övriga...
    2018 (Engelska)Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, nr 9, artikel-id 094413Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Density functional theory is a standard model for condensed-matter theory and computational material science. The accuracy of density functional theory is limited by the accuracy of the employed approximation to the exchange-correlation functional. Recently, the so-called strongly constrained appropriately normed (SCAN) [Sun, Ruzsinszky, and Perdew, Phys. Rev. Lett. 115, 036402 (2015)] functional has received a lot of attention due to promising results for covalent, metallic, ionic, as well as hydrogen- and van der Waals-bonded systems alike. In this work, we focus on assessing the performance of the SCAN functional for itinerant magnets by calculating basic structural and magnetic properties of the transition metals Fe, Co, and Ni. We find that although structural properties of bcc-Fe seem to be in good agreement with experiment, SCAN performs worse than standard local and semilocal functionals for fcc-Ni and hcp-Co. In all three cases, the magnetic moment is significantly overestimated by SCAN, and the 3d states are shifted to lower energies, as compared to experiments.

    Ort, förlag, år, upplaga, sidor
    AMER PHYSICAL SOC, 2018
    Nationell ämneskategori
    Teoretisk kemi
    Identifikatorer
    urn:nbn:se:liu:diva-151640 (URN)10.1103/PhysRevB.98.094413 (DOI)000444348500004 ()
    Anmärkning

    Funding Agencies|Swedish e-Science Research Centre (SeRC); Swedish Research Council (VR) through the International Career Grant [20146336]; Marie Sklodowska CurieActions, Cofund, Project [INCA 600398]; Swedish Foundation for Strategic Research (SSF) through the Future Research Leaders 6 program; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; competence center FunMat-II - Vinnova [201605156]; Russian Science Foundation [18-12-00492]

    Tillgänglig från: 2018-09-27 Skapad: 2018-09-27 Senast uppdaterad: 2019-05-14
  • 342.
    Gambino, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Titanium vacancy diffusion in TiN via non-equilibrium ab initio molecular dynamics2016Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Transition metal nitrides (TMNs) refractory ceramic materials are  widely employed as wear-resistant protective coatings in industrial machining as well as diffusion barriers inhibiting migration of metal impurities from the interconnects to the semiconducting region of electronic devices. TiN is the prototype of this class of materials and the most studied among TMNs. However, also for this system, a complete picture of the migration processes occurring at the atomic scale is still lacking. In this work I investigate the stability of Ti vacancy configurations and corresponding migration rates in TiN by means of density functional theory (DFT) calculations and ab-initio molecular dynamics simulations (AIMD). DFT calculations show that Ti vacancies tend to stay isolated because of repulsive interaction which decreases as the inverse of the distance between the vacancies.The equilibrium jump rate of single Ti vacancies in TiN is extrapolated temperature as a function of temperature from the results of non-equilibrium AIMD simulations accelerated by a bias force field according to the color diffusion algorithm. For each force field and, the jump occurrence times are fitted with the two parameters Gamma distribution in order to obtain the non equilibrium jump rate with the corresponding uncertainty. Extrapolated equilibrium values show an Arrhenius-like behavior, with activation energy Ea= (3.78 ± 0.28)eV and attempt frequency A = 4.45 (x3.6±1) x 1014 s-1.

  • 343.
    Gambino, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Max Planck Inst Eisenforsch GmbH, Germany.
    Lattice relaxations in disordered Fe-based materials in the paramagnetic state from first principles2018Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, nr 6, artikel-id 064105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first-principles calculation of many material properties, in particular related to defects and disorder, starts with the relaxation of the atomic positions of the system under investigation. This procedure is routine for nonmagnetic and magnetically ordered materials. However, when it comes to magnetically disordered systems, in particular the paramagnetic phase of magnetic materials, it is not clear how the relaxation procedure should be performed or which geometry should be used. Here we propose a method for the structural relaxation of magnetic materials in the paramagnetic regime, in an adiabatic fast-magnetism approximation within the disordered local moment (DLM) picture in the framework of density functional theory. The method is straightforward to implement using any ab initio code that allows for structural relaxations. We illustrate the importance of considering the disordered magnetic state during lattice relaxations by calculating formation energies and geometries for an Fe vacancy and C insterstitial atom in body-centered cubic (bcc) Fe as well as bcc Fe1-xCrx random alloys in the paramagnetic state. In the vacancy case, the nearest neighbors to the vacancy relax toward the vacancy of 0.14 angstrom (-5% of the ideal bcc nearest-neighbor distance), which is twice as large as the relaxation in the ferromagnetic case. The vacancy formation energy calculated in the DLM state on these positions is 1.60 eV, which corresponds to a reduction of about 0.1 eV compared to the formation energy calculated using DLM but on ferromagnetic-relaxed positions. The carbon interstitial formation energy is found to be 0.41 eV when the DLM relaxed positions are used, as compared to 0.59 eV when the FM-relaxed positions are employed. For bcc Fe0.5Cr0.5 alloys, the mixing enthalpy is reduced by 5 meV/atom, or about 10%, when the DLM state relaxation is considered, as compared to positions relaxed in the ferromagnetic state.

  • 344.
    Gambino, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Ruhr University of Bochum, Germany.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Max Planck Institute Eisenforsch GmbH, Germany.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. National University of Science and Technology MISIS, Russia.
    Nonequilibrium ab initio molecular dynamics determination of Ti monovacancy migration rates in B1 TiN2017Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, nr 10, artikel-id 104306Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use the color diffusion (CD) algorithm in nonequilibrium (accelerated) ab initio molecular dynamics simulations to determine Ti monovacancy jump frequencies in NaCl-structure titanium nitride (TiN), at temperatures ranging from 2200 to 3000 K. Our results showthat theCDmethod extended beyond the linear-fitting rate-versus-force regime [Sangiovanni et al., Phys. Rev. B 93, 094305 (2016)] can efficiently determine metal vacancy migration rates in TiN, despite the low mobilities of lattice defects in this type of ceramic compound. We propose a computational method based on gamma-distribution statistics, which provides unambiguous definition of nonequilibrium and equilibrium (extrapolated) vacancy jump rates with corresponding statistical uncertainties. The acceleration-factor achieved in our implementation of nonequilibrium molecular dynamics increases dramatically for decreasing temperatures from 500 for T close to the melting point T-m, up to 33 000 for T approximate to 0.7 T-m

  • 345.
    Garhammer, Julian
    et al.
    Univ Bayreuth, Germany.
    Hofmann, Fabian
    Univ Bayreuth, Germany.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Kuemmel, Stephan
    Univ Bayreuth, Germany.
    On the challenge to improve the density response with unusual gradient approximations2018Ingår i: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 91, nr 7, artikel-id 159Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Certain excitations, especially ones of long-range charge transfer character, are poorly described by time-dependent density functional theory (TDDFT) when typical (semi-)local functionals are used. A proper description of these excitations would require an exchange-correlation response differing substantially from the usual (semi-) local one. It has recently been shown that functionals of the generalized gradient approximation (GGA) type can yield unusual potentials, mimicking features of the exact exchange derivative discontinuity and showing divergences on orbital nodal surfaces. We here investigate whether these unusual potential properties translate into beneficial response properties. Using the Sternheimer formalism we closely investigate the response obtained with the 2013 exchange approximation by Armiento and Kummel (AK13) and the 1988 exchange approximation by Becke (B88), both of which show divergences on orbital nodal planes. Numerical calculations for Na-2 as well as analytical and numerical calculations for the hydrogen atom show that the response of AK13 behaves qualitatively different from usual semi-local functionals. However, the AK13 functional leads to fundamental instabilities in the asymptotic region that prevent its practical application in TDDFT. Our findings may help the development of future improved functionals. They also corroborate that the frequency-dependent Sternheimer formalism is excellently suited for running and analyzing TDDFT calculations.

  • 346.
    Gautam, Rekha
    et al.
    San Francisco State Univ, CA 94132 USA; Vanderbilt Univ, TN 37240 USA.
    Xiang, Yinxiao
    San Francisco State Univ, CA 94132 USA; Nankai Univ, Peoples R China; Nankai Univ, Peoples R China.
    Lamstein, Josh
    San Francisco State Univ, CA 94132 USA.
    Liang, Yi
    San Francisco State Univ, CA 94132 USA; Guangxi Univ, Peoples R China.
    Bezryadina, Anna
    San Francisco State Univ, CA 94132 USA; Calif State Univ Northridge, CA 91330 USA.
    Liang, Guo
    San Francisco State Univ, CA 94132 USA.
    Hansson, Tobias
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Quebec, Canada.
    Wetzel, Benjamin
    Univ Quebec, Canada; Univ Sussex, England.
    Preece, Daryl
    Univ Calif Irvine, CA USA.
    White, Adam
    San Francisco State Univ, CA 94132 USA.
    Silverman, Matthew
    San Francisco State Univ, CA 94132 USA.
    Kazarian, Susan
    San Francisco State Univ, CA 94132 USA.
    Xu, Jingjun
    Nankai Univ, Peoples R China.
    Morandotti, Roberto
    Univ Quebec, Canada; Univ Elect Sci and Tech China, Peoples R China; ITMO Univ, Russia.
    Chen, Zhigang
    San Francisco State Univ, CA 94132 USA; Nankai Univ, Peoples R China; Nankai Univ, Peoples R China.
    Optical force-induced nonlinearity and self-guiding of light in human red blood cell suspensions2019Ingår i: Light: Science & Applications, ISSN 2095-5545, E-ISSN 2047-7538, Vol. 8, artikel-id 31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Osmotic conditions play an important role in the cell properties of human red blood cells (RBCs), which are crucial for the pathological analysis of some blood diseases such as malaria. Over the past decades, numerous efforts have mainly focused on the study of the RBC biomechanical properties that arise from the unique deformability of erythrocytes. Here, we demonstrate nonlinear optical effects from human RBCs suspended in different osmotic solutions. Specifically, we observe self-trapping and scattering-resistant nonlinear propagation of a laser beam through RBC suspensions under all three osmotic conditions, where the strength of the optical nonlinearity increases with osmotic pressure on the cells. This tunable nonlinearity is attributed to optical forces, particularly the forward-scattering and gradient forces. Interestingly, in aged blood samples (with lysed cells), a notably different nonlinear behavior is observed due to the presence of free hemoglobin. We use a theoretical model with an optical force-mediated nonlocal nonlinearity to explain the experimental observations. Our work on light self-guiding through scattering bio-soft-matter may introduce new photonic tools for noninvasive biomedical imaging and medical diagnosis.

  • 347.
    Gebhardt, T
    et al.
    Rhein Westfal TH Aachen.
    Music, D
    Rhein Westfal TH Aachen.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Vitos, L
    Royal Institute Technology KTH.
    Dick, A
    Max Planck Institute Eisenforsch GmbH.
    Hickel, T
    Max Planck Institute Eisenforsch GmbH.
    Neugebauer, J
    Max Planck Institute Eisenforsch GmbH.
    Schneider, J M
    Rhein Westfal TH Aachen.
    The influence of additions of Al and Si on the lattice stability of fcc and hcp Fe-Mn random alloys2011Ingår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 23, nr 24, s. 246003-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have studied the influence of additions of Al and Si on the lattice stability of face-centred-cubic (fcc) versus hexagonal-closed-packed (hcp) Fe-Mn random alloys, considering the influence of magnetism below and above the fcc Neel temperature. Employing two different ab initio approaches with respect to basis sets and treatment of magnetic and chemical disorder, we are able to quantify the predictive power of the ab initio methods. We find that the addition of Al strongly stabilizes the fcc lattice independent of the regarded magnetic states. For Si a much stronger dependence on magnetism is observed. Compared to Al, almost no volume change is observed as Si is added to Fe-Mn, indicating that the electronic contributions are responsible for stabilization/destabilization of the fcc phase.

  • 348.
    Gebhardt, T.
    et al.
    Rhein Westfal TH Aachen.
    Music, D.
    Rhein Westfal TH Aachen.
    Hallstedt, B.
    Rhein Westfal TH Aachen.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Vitos, L.
    Royal Institute of Technology.
    M. Schneider, J.
    Rhein Westfal TH Aachen.
    Ab initio lattice stability of fcc and hcp Fe-Mn random alloys2010Ingår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 22, nr 29, s. 295402-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have studied the lattice stability of face centred cubic (fcc) versus hexagonal close packed (hcp) Fe-Mn random alloys using ab initio calculations. In the calculations we considered the antiferromagnetic order of local moments, which for fcc alloys models the magnetic configuration of this phase at room temperature (below its Neel temperature) as well as their complete disorder, corresponding to paramagnetic fcc and hcp alloys. For both cases, the results are consistent with our thermodynamic calculations, obtained within the Calphad approach. For the room temperature magnetic configuration, the cross-over of the total energies of the hcp phase and the fcc phase of Fe-Mn alloys is at the expected Mn content, whereas for the magnetic configuration above the fcc Neel temperature, the hcp lattice is more stable within the whole composition range studied. The increase of the total energy difference between hcp and antiferromagnetic fcc due to additions of Mn as well as the stabilizing effect of antiferromagnetic ordering on the fcc phase are well displayed. These results are of relevance for understanding the deformation mechanisms of these random alloys.

  • 349.
    Gebhardt, T
    et al.
    Rhein Westfal TH Aachen.
    Music, Denis
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    von Appen, J
    Rhein Westfal TH Aachen.
    Dronskowski, R
    Rhein Westfal TH Aachen.
    Wagner, D
    Rhein Westfal TH Aachen.
    Mayer, J
    Rhein Westfal TH Aachen.
    Schneider, J M
    Rhein Westfal TH Aachen.
    Influence of chemical composition and magnetic effects on the elastic properties of fcc Fe-Mn alloys2011Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 59, nr 4, s. 1493-1501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of the Mn content on the elastic properties of face centered cubic Fe-Mn alloys was studied using the combinatorial approach. Fe-Mn thin films with a graded chemical composition were synthesized. Nanoindentation experiments were carried out to investigate the elastic properties as a function of the Mn content. As the Mn content increases from similar to 23 to similar to 39 at.%, the average bulk modulus varies from 143 to 105 GPa. Ab initio calculations served to probe the impact of magnetic effects on the elastic properties. The magnetic state description with disordered local moments yields the best agreement with the experimental results, whereas with non-magnetic and antiferromagnetic configurations the bulk modulus is overestimated. The strong impact of the magnetic configuration may be understood based on the differences in the chemical bonding and the magnetovolume effect. It is suggested that, owing to minute energy differences of competing antiferromagnetic configurations, a mixture of these with a "notional magnetic disorder" is present, which is in fact well described by the disordered local moments model. These results show that the combinatorial thin film synthesis with subsequent nanoindentation is an appropriate tool for investigating the elastic properties of Fe-Mn alloys systematically as a function of the chemical composition, to validate theoretical models.

  • 350.
    Gebhardt, Thomas
    et al.
    Rhein Westfal TH Aachen.
    Music, Denis
    Rhein Westfal TH Aachen.
    Kossmann, Daniel
    Rhein Westfal TH Aachen.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Vitos, Levente
    Royal Institute Technology, SE-75121 Uppsala, Sweden .
    Schneider, Jochen M
    Rhein Westfal TH Aachen.
    Elastic properties of fcc Fe-Mn-X (X = Al, Si) alloys studied by theory and experiment2011Ingår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 59, nr 8, s. 3145-3155Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have studied the influence of Al and Si additions on the elastic properties of face-centered cubic (fcc) Fe-Mn random alloys with Fe/Mn ratios of 4.00 and 2.33 using ab initio calculations. When Al is added up to 8 at.% the shearing elastic constants (C-11-C-12)/2 and C-44 decrease, resulting in a drop of similar to 20% in shear and similar to 19% in Youngs modulus. In fcc Fe-Mn-Si alloys, the trends in the elastic constants are similar, but less drastic, with a similar to 7% shear and similar to 6% Youngs modulus decrease when Si is added up to 8 at.%. The Fe/Mn ratio exhibits a minor influence on the shear and Youngs modulus values at constant Al and Si contents. To assess the quality of the ab initio data Fe-Mn-Al and Fe-Mn-Si thin films with an fcc structure were combinatorially synthesized and the elastic properties measured using nanoindentation. For both systems the measured and calculated lattice parameters are in good agreement. Although the measured Youngs modulus data showed significant scatter due to the high surface roughness, they are in good agreement with the predicted values. For the Fe-Mn-Al system the calculations generally underestimate the experimental data by similar to 15%. For the Fe-Mn-Si system the calculated data are in general lower by similar to 10% than the experimentally determined values. The presented results are of relevance for multicomponent alloy design, since the effect of Si and Al addition on the elastic properties of Fe-Mn alloys can be predicted based on ab initio data.

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