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Lambrix, P., Armiento, R., Delin, A. & Li, H. (2018). Big Semantic Data Processing in the Materials Design Domain. In: Sherif Sakr and Albert Zomaya (Ed.), Encyclopedia of Big Data Technologies: . Cham: Springer
Open this publication in new window or tab >>Big Semantic Data Processing in the Materials Design Domain
2018 (English)In: Encyclopedia of Big Data Technologies / [ed] Sherif Sakr and Albert Zomaya, Cham: Springer, 2018Chapter in book (Refereed)
Abstract [en]

To speed up the progress in the field of materials design, a number of challenges related to big data need to be addressed. This entry discusses these challenges and shows the semantic technologies that alleviate the problems related to variety, variability, and veracity.

Place, publisher, year, edition, pages
Cham: Springer, 2018
National Category
Computer Sciences Materials Engineering
Identifiers
urn:nbn:se:liu:diva-147715 (URN)10.1007/978-3-319-63962-8_293-1 (DOI)9783319639628 (ISBN)
Funder
Swedish e‐Science Research Center
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-05-07Bibliographically approved
Nuala, M., Johansson, L. I., Xia, C., Armiento, R., Abrikosov, I. & Jacobi, C. (2016). Structural and electronic properties of Li-intercalated graphene on SiC(0001). Physical Review B: covering condensed matter and materials physics, 93(19), 195421-1-195421-9
Open this publication in new window or tab >>Structural and electronic properties of Li-intercalated graphene on SiC(0001)
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2016 (English)In: Physical Review B: covering condensed matter and materials physics, ISSN 2469-9950, Vol. 93, no 19, p. 195421-1-195421-9Article in journal (Refereed) Published
Abstract [en]

We investigate the structural and electronic properties of Li-intercalated monolayer graphene on SiC(0001) using combined angle-resolved photoemission spectroscopy and first-principles density functional theory. Li intercalates at room temperature both at the interface between the buffer layer and SiC and between the two carbon layers. The graphene is strongly n-doped due to charge transfer from the Li atoms and two pi bands are visible at the (K) over bar point. After heating the sample to 300 degrees C, these pi bands become sharp and have a distinctly different dispersion to that of Bernal-stacked bilayer graphene. We suggest that the Li atoms intercalate between the two carbon layers with an ordered structure, similar to that of bulk LiC6. An AA stacking of these two layers becomes energetically favourable. The pi bands around the (K) over bar point closely resemble the calculated band structure of a C6LiC6 system, where the intercalated Li atoms impose a superpotential on the graphene electronic structure that opens gaps at the Dirac points of the two pi cones.

Place, publisher, year, edition, pages
American Physical Society, 2016
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-129161 (URN)10.1103/PhysRevB.93.195421 (DOI)000376248200006 ()
Note

Funding Agencies|Swedish Research Council (VR) [621-2011-4252, 621-2011-4426]; Swedish Foundation for Strategic Research (SSF) program [10-0026]; European Union Seventh Framework Programme, Graphene Flagship [604391]; Swedish Government Strategic Research Areas SeRC and in Materials Science on Functional Materials at Link oping University [2009 00971]; SRC VR Grant [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR; Grant of Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Tomsk State University Academic D. I. Mendeleev Fund Program [8.1.18.2015]

Available from: 2016-06-13 Created: 2016-06-13 Last updated: 2016-07-11Bibliographically approved
Alling, B., Högberg, H., Armiento, R., Rosén, J. & Hultman, L. (2015). A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary (M1-xMxB2)-M-1-B-2 alloys with AlB2 type structure. Scientific Reports, 5
Open this publication in new window or tab >>A theoretical investigation of mixing thermodynamics, age-hardening potential, and electronic structure of ternary (M1-xMxB2)-M-1-B-2 alloys with AlB2 type structure
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2015 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5Article in journal (Refereed) Published
Abstract [en]

Transition metal diborides are ceramic materials with potential applications as hard protective thin films and electrical contact materials. We investigate the possibility to obtain age hardening through isostructural clustering, including spinodal decomposition, or ordering-induced precipitation in ternary diboride alloys. By means of first-principles mixing thermodynamics calculations, 45 ternary (M1-xMxB2)-M-1-B-2 alloys comprising (MB2)-B-i (M-i = Mg, Al, Sc, Y, Ti, Zr, Hf, V, Nb, Ta) with AlB2 type structure are studied. In particular Al1-xTixB2 is found to be of interest for coherent isostructural decomposition with a strong driving force for phase separation, while having almost concentration independent a and c lattice parameters. The results are explained by revealing the nature of the electronic structure in these alloys, and in particular, the origin of the pseudogap at E-F in TiB2, ZrB2, and HfB2.

Place, publisher, year, edition, pages
Nature Publishing Group: Open Access Journals - Option C / Nature Publishing Group, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-119589 (URN)10.1038/srep09888 (DOI)000355215100001 ()25970763 (PubMedID)
Note

Funding Agencies|Swedish Research Council (VR) [621-2011-4417, 621-2011-4249]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Knut and Alice Wallenberg Foundation; ERC [258509]

Available from: 2015-06-23 Created: 2015-06-22 Last updated: 2017-12-04
Nuala, M. C., Armiento, R., Yakimova, R. & Abrikosov, I. (2015). Charge neutrality in epitaxial graphene on 6H-SiC(0001) via nitrogen intercalation. Physical Review B. Condensed Matter and Materials Physics, 92(8), Article ID 081409.
Open this publication in new window or tab >>Charge neutrality in epitaxial graphene on 6H-SiC(0001) via nitrogen intercalation
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 92, no 8, article id 081409Article in journal (Refereed) Published
Abstract [en]

The electronic properties of epitaxial graphene grown on SiC(0001) are known to be impaired relative to those of freestanding graphene. This is due to the formation of a carbon buffer layer between the graphene layers and the substrate, which causes the graphene layers to become strongly n-doped. Charge neutrality can be achieved by completely passivating the dangling bonds of the clean SiC surface using atomic intercalation. So far, only one element, hydrogen, has been identified as a promising candidate. We show, using first-principles density functional calculations, how it can also be accomplished via the growth of a thin layer of silicon nitride on the SiC surface. The subsequently grown graphene layers display the electronic properties associated with charge neutral graphene. We show that the surface energy of this structure is considerably lower than that of others with intercalated atomic nitrogen and determine how its stability depends on the N-2 chemical potential.

Place, publisher, year, edition, pages
American Physical Society, 2015
National Category
Condensed Matter Physics Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-121104 (URN)10.1103/PhysRevB.92.081409 (DOI)000359861600002 ()
Note

Funding Agencies|European Union [604391]; Swedish Research Council (VR) [621-2011-4426]; Swedish Foundation for Strategic Research (SSF) program SRL Grant [10-0026]; VR Grant [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR; Grant of Ministry of Education and Science of the Russian Federation [14.Y26.31.0005]; Tomsk State University Academic D. I. Mendeleev Fund Program [8.1.18.2015]

Available from: 2015-09-07 Created: 2015-09-07 Last updated: 2017-12-04
Faber, F., Lindmaa, A., von Lilienfeld, O. A. & Armiento, R. (2015). Crystal structure representations for machine learning models of formation energies. International Journal of Quantum Chemistry, 115(16), 1094-1101
Open this publication in new window or tab >>Crystal structure representations for machine learning models of formation energies
2015 (English)In: International Journal of Quantum Chemistry, ISSN 0020-7608, E-ISSN 1097-461X, Vol. 115, no 16, p. 1094-1101Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Wiley, 2015
Keywords
machine learning; formation energies; representations; crystal structure; periodic systems
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-120326 (URN)10.1002/qua.24917 (DOI)000357606000010 ()
Note

Funding Agencies|Swedish Research Council (VR) [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials - VR; Swiss National Science foundation [PP00P2_138932]; Office of Science of the U.S. DOE [DE-AC02-06CH11357]; Air Force Office of Scientific Research, Air Force Material Command, USAF [FA9550-15-1-0026]

Available from: 2015-07-31 Created: 2015-07-31 Last updated: 2017-11-01
Vlcek, V., Steinle-Neumann, G., Leppert, L., Armiento, R. & Kuemmel, S. (2015). Improved ground-state electronic structure and optical dielectric constants with a semilocal exchange functional. Physical Review B. Condensed Matter and Materials Physics, 91(3), 035107
Open this publication in new window or tab >>Improved ground-state electronic structure and optical dielectric constants with a semilocal exchange functional
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2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 3, p. 035107-Article in journal (Refereed) Published
Abstract [en]

A recently published generalized gradient approximation functional within density functional theory (DFT) has shown, in a few paradigm tests, an improved KS orbital description over standard (semi) local approximations. The characteristic feature of this functional is an enhancement factor that diverges like s ln(s) for large reduced density gradients s which leads to unusual properties. We explore the improved orbital description of this functional more thoroughly by computing the electronic band structure, band gaps, and the optical dielectric constants in semiconductors, Mott insulators, and ionic crystals. Compared to standard semilocal functionals, we observe improvement in both the band gaps and the optical dielectric constants. In particular, the results are similar to those obtained with orbital functionals or by perturbation theory methods in that it opens band gaps in systems described as metallic by standard (semi) local density functionals, e. g., Ge, alpha-Sn, and CdO.

Place, publisher, year, edition, pages
American Physical Society, 2015
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-114585 (URN)10.1103/PhysRevB.91.035107 (DOI)000348703700002 ()
Note

Funding Agencies|Deutsche Forschungsgemeinschaft (DFG) [STE1105/8-1, SFB840, B1]; Swedish Research Council [621-2011-4249]; VR

Available from: 2015-02-27 Created: 2015-02-26 Last updated: 2017-12-04
Zhu, H., Sun, W., Armiento, R., Lazić, P. & Ceder, G. (2014). Band structure engineering through orbital interaction for enhanced thermoelectric power factor. Applied Physics Letters, 104, 082107-1-082107-5
Open this publication in new window or tab >>Band structure engineering through orbital interaction for enhanced thermoelectric power factor
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2014 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 104, p. 082107-1-082107-5Article in journal (Refereed) Published
Abstract [en]

Band structure engineering for specific electronic or optical properties is essential for the further development of many important technologies including thermoelectrics, optoelectronics, and microelectronics. In this work, we report orbital interaction as a powerful tool to finetune the band structure and the transport properties of charge carriers in bulk crystalline semiconductors. The proposed mechanism of orbital interaction on band structure is demonstrated for IV-VI thermoelectric semiconductors. For IV-VI materials, we find that the convergence of multiple carrier pockets not only displays a strong correlation with the s-p and spin-orbit coupling but also coincides with the enhancement of power factor. Our results suggest a useful path to engineer the band structure and an enticing solid-solution design principle to enhance thermoelectric performance.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2014
Keywords
Thermoelectrics, Band structure, Power factor, Seebeck effect
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-105274 (URN)10.1063/1.4866861 (DOI)000332619100064 ()
Funder
Swedish Research Council, 621-2011-4249
Available from: 2014-03-14 Created: 2014-03-14 Last updated: 2017-12-05Bibliographically approved
Armiento, R., Kozinsky, B., Hautier, G., Fornari, M. & Ceder, G. (2014). High-throughput screening of perovskite alloys for piezoelectric performance and thermodynamic stability. Physical Review B. Condensed Matter and Materials Physics, 89(13), 134103
Open this publication in new window or tab >>High-throughput screening of perovskite alloys for piezoelectric performance and thermodynamic stability
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2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 13, p. 134103-Article in journal (Refereed) Published
Abstract [en]

We screen a large chemical space of perovskite alloys for systems with optimal properties to accommodate a morphotropic phase boundary (MPB) in their composition-temperature phase diagram, a crucial feature for high piezoelectric performance. We start from alloy end points previously identified in a high-throughput computational search. An interpolation scheme is used to estimate the relative energies between different perovskite distortions for alloy compositions with a minimum of computational effort. Suggested alloys are further screened for thermodynamic stability. The screening identifies alloy systems already known to host an MPB and suggests a few others that may be promising candidates for future experiments. Our method of investigation may be extended to other perovskite systems, e.g., (oxy-)nitrides, and provides a useful methodology for any application of high-throughput screening of isovalent alloy systems.

Place, publisher, year, edition, pages
American Physical Society, 2014
Keywords
High-throughput, DFT, piezoelectric, thermodynamic stability
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-106609 (URN)10.1103/PhysRevB.89.134103 (DOI)000337285000001 ()
Funder
Swedish Research Council, 621-2011-4249
Available from: 2014-05-14 Created: 2014-05-14 Last updated: 2017-12-05Bibliographically approved
Johansson, L. I., Armiento, R., Avila, J., Xia, C., Lorcy, S., Igor A., A., . . . Virojanadara, C. (2014). Multiple π-bands and Bernal stacking of multilayer graphene on C-face SiC, revealed by nano-Angle Resolved Photoemission. Scientific Reports, 4(4157)
Open this publication in new window or tab >>Multiple π-bands and Bernal stacking of multilayer graphene on C-face SiC, revealed by nano-Angle Resolved Photoemission
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2014 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 4, no 4157Article in journal (Refereed) Published
Abstract [en]

Only a single linearly dispersing π-band cone, characteristic of monolayer graphene, has so far been observed in Angle Resolved Photoemission (ARPES) experiments on multilayer graphene grown on C-face SiC. A rotational disorder that effectively decouples adjacent layers has been suggested to explain this. However, the coexistence of μm-sized grains of single and multilayer graphene with different azimuthal orientations and no rotational disorder within the grains was recently revealed for C-face graphene, but conventional ARPES still resolved only a single π-band. Here we report detailed nano-ARPES band mappings of individual graphene grains that unambiguously show that multilayer C-face graphene exhibits multiple π-bands. The band dispersions obtained close to the K-point moreover clearly indicate, when compared to theoretical band dispersion calculated in the framework of the density functional method, Bernal (AB) stacking within the grains. Thus, contrary to earlier claims, our findings imply a similar interaction between graphene layers on C-face and Si-face SiC.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
Keywords
Electronic properties and materials, Graphene, Stacking
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-105279 (URN)10.1038/srep04157 (DOI)000331885900004 ()
Funder
Swedish Research Council, 621-2011-4252Swedish Research Council, 621-2011-4249Swedish Foundation for Strategic Research , 10-0026
Available from: 2014-03-14 Created: 2014-03-14 Last updated: 2017-12-05Bibliographically approved
Lindmaa, A., Mattsson, A. E. & Armiento, R. (2014). Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas. Physical Review B. Condensed Matter and Materials Physics, 90(7), 075139
Open this publication in new window or tab >>Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas
2014 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, no 7, p. 075139-Article in journal (Refereed) Published
Abstract [en]

We derive a closed-form expression for the quantum corrections to the kinetic energy density in the Thomas-Fermi limit of a linear potential model system in three dimensions (the Airy gas). The universality of the expression is tested numerically in a number of three-dimensional model systems: (i) jellium surfaces, (ii) confinement in a hydrogenlike potential (the Bohr atom), (iii) particles confined by a harmonic potential in one and (iv) all three dimensions, and (v) a system with a cosine potential (the Mathieu gas). Our results confirm that the usual gradient expansion of extended Thomas-Fermi theory does not describe the quantum oscillations for systems that incorporate surface regions where the electron density drops off to zero. We find that the correction derived from the Airy gas is universally applicable to relevant spatial regions of systems of types (i), (ii), and (iv), but somewhat surprisingly not (iii). We discuss possible implications of our findings to the development of functionals for the kinetic energy density.

Place, publisher, year, edition, pages
American Physical Society, 2014
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-110971 (URN)10.1103/PhysRevB.90.075139 (DOI)000341238200002 ()
Note

Funding Agencies|Swedish Research Council (VR) [621-2011-4249]; Linnaeus Environment at Linkoping on Nanoscale Functional Materials (LiLi-NFM) - VR; U.S. Department of Energys National Nuclear Security Administration [DE-AC04-94AL85000]

Available from: 2014-10-02 Created: 2014-10-01 Last updated: 2017-12-05
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-5571-0814

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