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  • 1.
    Barta, P.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Dannetun, Per
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Zagórska, M.
    Department of Chemistry, Technical University of Warsaw, PL‐00 664 Warsaw, Poland.
    Pron, A.
    Department of Material Science and Ceramics, Academy of Mining and Metallurgy, PL‐30 059 Kraków, Poland.
    Temperature evolution of the electronic band structure of the undoped and doped regioregular analog of poly(3‐alkylthiophenes): A spectroscopic and theoretical study1994In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 100, no 2, p. 1731-1741Article in journal (Refereed)
    Abstract [en]

    The undoped and ferric chloride p‐doped ‘‘head‐to‐head’’ ‘‘tail‐to‐tail’’ analog of poly(3‐decylthiophene) obtained from substituted bithiophenes, i.e., poly(4,4’didecyl‐2,2’bithiophene)‐PDDBT has been investigated. The samples were studied by means of ultraviolet photoelectron spectroscopy,optical absorption measurements, and polymerbands structure calculations. Experiments were carried out at different temperatures between 100 °C and −180 °C. The results indicate that PDDBT is nonplanar in the undoped state. No temperature effects have been observed in the π‐electron properties. In the doped state, however, lowering of the temperature results in an increase of the system planarity that modifies the electronic band structure. This effect has been shown to be fully reversible with temperature.

  • 2.
    Boström, Mathias
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Lima, E. R. A.
    Universidade Federal do Rio de Janeiro,.
    Tavares,, F. W.
    Universidade Federal do Rio de Janeiro,.
    Ninham, B. W.
    Australian National University, Canberra.
    The influence of ion binding and ion specific potentials on the double layer pressure between charged bilayers at low salt concentrations2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, p. 135104-1-135104-4Article in journal (Refereed)
  • 3.
    Castleton, Christopher
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Kullgren, J.
    Department of Materials Chemistry, Uppsala University, Box 538, SE-75121, Sweden.
    Hermansson, K.
    Department of Materials Chemistry, Uppsala University, Box 538, SE-75121, Sweden.
    Tuning LDA+U for electron localization and structure at oxygen vacancies in ceria2007In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 24Article in journal (Refereed)
    Abstract [en]

    We examine the real space structure and the electronic structure (particularly Ce4f electron localization) of oxygen vacancies in Ce O2 (ceria) as a function of U in density functional theory studies with the rotationally invariant forms of the LDA+U and GGA+U functionals. The four nearest neighbor Ce ions always relax outwards, with those not carrying localized Ce4f charge moving furthest. Several quantification schemes show that the charge starts to become localized at U˜3 eV and that the degree of localization reaches a maximum at ~6 eV for LDA+U or at ~5.5 eV for GGA+U. For higher U it decreases rapidly as charge is transferred onto second neighbor O ions and beyond. The localization is never into atomic corelike states, at maximum localization about 80-90% of the Ce4f charge is located on the two nearest neighboring Ce ions. However, if we look at the total atomic charge we find that the two ions only make a net gain of (0.2-0.4) e each, so localization is actually very incomplete, with localization of Ce4f electrons coming at the expense of moving other electrons off the Ce ions. We have also revisited some properties of defect-free ceria and find that with LDA+U the crystal structure is actually best described with U=3-4 eV, while the experimental band structure is obtained with U=7-8 eV. (For GGA+U the lattice parameters worsen for U>0 eV, but the band structure is similar to LDA+U.) The best overall choice is U˜6 eV with LDA+U and ˜5.5 eV for GGA+U, since the localization is most important, but a consistent choice for both Ce O2 and Ce2 O3, with and without vacancies, is hard to find. © 2007 American Institute of Physics.

  • 4. Cavalleri, M
    et al.
    Näslund, LÅ
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Edwards, DC
    Wernet, Ph
    Ogasawara, H
    Myneni, S
    Ojamäe, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry.
    Odelius, M
    Nilsson, A
    Pettersson, LGM
    The local structure of protonated water from x-ray absorption and density functional theory2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, p. 194508-194508Article in journal (Refereed)
    Abstract [en]

      

  • 5.
    Ciobanu, C V
    et al.
    Ohio State Univ, Dept Phys, Columbus, OH 43210 USA.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology.
    Shavitt, I
    Ohio State Univ, Dept Phys, Columbus, OH 43210 USA.
    Singer, S J
    Ohio State Univ, Dept Phys, Columbus, OH 43210 USA.
    Structure and vibrational spectra of H(+)(H(2)O)(8): Is the excess proton in a symmetrical hydrogen bond?2000In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 113, no 13, p. 5321-5330, article id PII [S0021-9606(00)30735-8]Article in journal (Refereed)
    Abstract [en]

    The energetics, structure, and vibrational spectra of a wide variety of H + (H 2 O) 8 structures are calculated using density functional theory and second-order Møller–Plesset ab initio methods. In these isomers of H + (H 2 O) 8 the local environment of the excess proton sometimes resembles a symmetric H 5 O + 2 structure and sometimes H 3 O + , but many structures are intermediate between these two limits. We introduce a quantitative measure of the degree to which the excess proton resembles H 5 O + 2 or H 3 O + . Other bond lengths and, perhaps most useful, the position of certain vibrational bands track this measure of the symmetry in the local structure surrounding the excess proton. The general trend is for the most compact structures to have the lowest energy. However, adding zero-point energy counteracts this trend, making prediction of the most stable isomer impossible at this time. At elevated temperatures corresponding to recent experiments and atmospheric conditions (150–200 K), calculated Gibbs free energies clearly favor the least compact structures, in agreement with recent thermal simulations [Singer, McDonald, and Ojamäe, J. Chem. Phys. 112, 710 (2000)]. © 2000 American Institute of Physics.

  • 6.
    Crispin, Annica
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Dos, Santos D.A.
    Dos Santos, D.A., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Cornil, J.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Johansson, N.
    Bauer, J.
    Covion Organic Semiconductors GmbH, Industrial Park Hoechst, D-65926 Frankfurt, Germany.
    Weissortel, F.
    Weissörtel, F., Electrochemistry and Optoelectronic Materials, FB 6, University Duisburg, D-47048 Duisburg, Germany.
    Salbeck, J.
    Electrochemistry and Optoelectronic Materials, FB 6, University Duisburg, D-47048 Duisburg, Germany, Macromolecular Chemistry and Molecular Materials, FB 18, University Kassel, D-34132 Kassel, Germany.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, Tucson, AZ 85721-0041, United States.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Influence of dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors2002In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 116, no 18, p. 8159-8167Article in journal (Refereed)
    Abstract [en]

    The influence of the dopant on the electronic structure of spiro-oligophenyl-based disordered organic semiconductors was studied by means of photoelectron spectroscopy. With lithium atoms as dopants, two charges were stored on the same spiro branch in the form of bipolarons, for spiro-quarterphenyl and spiro-sexiphenyl. For doping with the sodium atoms, the size of the counter ions made it less energetically desirable to store two charges onto a single branch, and the charged species were polarons independent of the level of doping which was confirmed by optical absorption data.

  • 7.
    Crispin, Annica
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Jonsson, A.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Aluminum-barium interfaces on some processable poly(p-phenylene vinylene) polymers studied by photoelectron spectroscopy2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 115, no 11, p. 5252-5257Article in journal (Refereed)
    Abstract [en]

    The control of the deposition of metals on the surface of conjugated polymers determined the electronic properties of the electrical contacts. X ray photoelectron spectroscopy (XPS) and ultraviolet photon spectroscopy (UPS) was used to study the influence of an intermediate layer of barium atoms on the chemical effects that occured during the deposition of aluminium atoms of substituted poly(p-phenylvinylene) polymers. The thin films were prepared on gold substrates for spectroscopy by spin coating techniques. The diffusion of the aluminium atoms occured when the side grops were bulky and therby resulted in porous polymer films.

  • 8.
    Crispin, X
    et al.
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    Geskin, VM
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    Bureau, C
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    Lazzaroni, R
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    Schmickler, W
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    Bredas, JL
    Univ Mons, Ctr Rech Elect & Photon Mol, Serv Chim Mat Nouveaux, B-7000 Mons, Belgium CEA Saclay, DSM, DRECAM, SRSIM, F-91191 Gif Sur Yvette, France Univ Ulm, Dept Electrochem, D-89069 Ulm, Germany Univ Arizona, Dept Chem, Tucson, AZ 85721 USA.
    A density functional model for tuning the charge transfer between a transition metal electrode and a chemisorbed molecule via the electrode potential2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 115, no 22, p. 10493-10499Article in journal (Refereed)
    Abstract [en]

    A simple approach is proposed to predict the magnitude of charge transfer between a polarized transition metal electrode and a chemisorbed molecule in an electrolytic solution. The approach is based on the equalization of the chemical potentials, as defined in density-functional theory (DFT). The system is modeled by a metal cluster, a molecule, and a set of point charges (counter ions) and the properties evaluated using methods derived from DFT, specifically, we study here the chemisorption of acrylonitrile on nickel. This approach allows us to point out the various factors determining the charge transfer. The results show a linear increase in the amount of charge transferred to the chemisorbed molecule with the polarization of the metal electrode. (C) 2001 American Institute of Physics.

  • 9.
    Crispin, Xavier
    et al.
    University of Mons, Belgium.
    Bureau, C.
    CEA Saclay, France;.
    Geskin, V. M.
    University of Mons, Belgium.
    Lazzaroni, R.
    University of Mons, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Bredas, J. L.
    University of Mons, Belgium.
    Chemisorption of acrylonitrile on the Cu(100) surface: A local density functional study1999In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 111, no 7, p. 3237-3251Article in journal (Refereed)
    Abstract [en]

    The possibility of chemically grafting polyacrylonitrile onto transition metal electrodes via electropolymerization leads to promising applications in the fields of corrosion protection or metal surface functionalization. The initial step of the electrografting mechanism is the adsorption of the acrylonitrile monomer on the metal surface from solution. Here, we investigate theoretically this adsorption process on the copper (100) surface; Density Functional Theory is used in the Local Spin Density approximation to describe the electronic and structural properties of acrylonitrile adsorbed on copper clusters. The chemisorption of acrylonitrile on the copper surface is confirmed experimentally via X-Ray Photoelectron Spectroscopy. The thermodynamic characteristics of the adsorption process are also studied via statistical mechanics. Finally, determining the influence of the copper cluster size on the adsorption of acrylonitrile allows to extrapolate the properties of the acrylonitrile/Cu(100) surface from those of acrylonitrile/copper clusters. (C) 1999 American Institute of Physics. [S0021-9606(99)70231-X].

  • 10.
    Cronstrand, P.
    et al.
    Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Luo, Y.
    Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, SCFAB, SE-106 91 Stockholm, Sweden.
    Few-states models for three-photon absorption2004In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 5, p. 2020-2029Article in journal (Refereed)
    Abstract [en]

    The validity of few-states models for several systems ranging from lithium hydride to a series of large p-conjugated systems was discussed. Various aspects of the models which include convergence, behavior, merits and shortcomings were studied. The role of various characteristics of the electronic structure such as symmetry and charge transfer was elaborated. Analysis suggests that few-states models can be useful for interpretation purposes when applied to three-photon absorption.

  • 11.
    Cukras, Janusz
    et al.
    University of Trieste, Italy.
    Coriani, Sonia
    University of Trieste, Italy.
    Decleva, Piero
    University of Trieste, Italy.
    Christiansen, Ove
    Aarhus University, Denmark.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Photoionization cross section by Stieltjes imaging applied to coupled cluster Lanczos pseudo-spectra2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 139, no 9Article in journal (Refereed)
    Abstract [en]

    A recently implemented asymmetric Lanczos algorithm for computing (complex) linear response functions within the coupled cluster singles (CCS), coupled cluster singles and iterative approximate doubles (CC2), and coupled cluster singles and doubles (CCSD) is coupled to a Stieltjes imaging technique in order to describe the photoionization cross section of atoms and molecules, in the spirit of a similar procedure recently proposed by Averbukh and co-workers within the Algebraic Diagrammatic Construction approach. Pilot results are reported for the atoms He, Ne, and Ar and for the molecules H2, H2O, NH3, HF, CO, and CO2.

  • 12.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Boman, Magnus
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Fredriksson, C.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Brédas, J. L.
    Service de Chimie des Matériaux Nouveaux, Département des Matériaux et Procédés, Université de Mons‐Hainaut, Belgium.
    Zamboni, R.
    Istituto di Spettroscopia Molecolare, CNR, Bologna, Italy.
    Taliani, C.
    Istituto di Spettroscopia Molecolare, CNR, Bologna, Italy.
    The chemical and electronic structure of the interface between aluminum and polythiophene semiconductors1993In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 99, no 1, p. 664-672Article in journal (Refereed)
    Abstract [en]

    We have investigated the chemical nature and the electronic structure of the interface between a low work function metal,aluminum, and a conjugated polymersemiconductor, polythiophene. We have studied the initial stages of the interface formation by depositing the metal onto the surface of a polymer film. Charge transfer processes between the metal and the polymer are analyzed using core‐level x‐ray photoelectron spectroscopy (XPS); the evolution upon metallization of the valence electronic levels directly related to the polymerelectronic structure is followed with ultraviolet photoelectron spectroscopy (UPS). With these techniques, we investigate the deposition of aluminum on two polythiophene systems (i) the alkyl‐substituted poly‐3‐octylthiophene and (ii) the α‐sexithiophene oligomer. The experimental data are compared to the results of a recent quantum chemical study on model systems consisting of thiophene oligomers (up to sexithiophene) interacting with a few Al atoms. The interaction of polythiophene with Al atoms is found to modify dramatically the structure of the conjugated backbone, as strong carbon–aluminum bonds are formed in the α positions of the thiophene rings. A large charge transfer takes place from the Al atoms to the polymer chain, and the upper π levels of the polymer are strongly affected. The metallization is contrasted to the doping of conjugated polymers with alkali metals

  • 13.
    Dannetun, Per
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lögdlund, Michael
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Fredriksson, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Lazzaroni, R.
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Fauquet, C.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Spangler, C. W.
    Department of Chemistry, Northern Illinois University, Dekalb, Illinois 60115, USA.
    Bredás, J. L.
    Service de Chimie des Matériaux Nouveaux, Université de Mons‐Hainaut, Place du Parc 20, B‐7000 Mons, Belgium.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Reactions of low work function metals Na, Al, and Ca on α,ω-€diphenyltetradecaheptaene. Implications for metal/polymer interfaces1994In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 100, no 9, p. 6765-6771Article in journal (Refereed)
    Abstract [en]

    The interactions between different low work function metals aluminium,calcium and sodium, and α,ω‐diphenyltetradecaheptaene, a model molecule for certain conjugated polymers, have been investigated using both x‐ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The spectra are interpreted with the help of the results of quantum chemical calculations performed within the local spin density (LSD) approximation methodology. The metals are found to interact with the conjugated system in very different ways. Aluminium forms a covalent bond, which strongly modifies the π‐electronic structure of the conjugated molecule, while both the sodium and the calcium atoms act as doping agents, inducing new states in the otherwise forbidden bandgap. These new gap states can be viewed as a soliton–antisoliton pair for the Na/DP7 and a bipolaronic‐like defect for Ca/DP7.

  • 14.
    de Jong, Michel P
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Van, Der Gon A.W.D.
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Osikowicz, Wojciech
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Groenendaal, L.
    Agfa-Gevaert N.V., R and D Materials - Chemistry Dept., Septestraat 27, B-2640 Mortsel, Belgium.
    The electronic structure of n- and p-doped phenyl-capped 3,4-ethylenedioxythiophene trimer2003In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 118, no 14, p. 6495-6502Article in journal (Refereed)
    Abstract [en]

    A study was conducted on the effects of chemical doping on the chemical and electronic structure of condensed molecular solid films of the ethylenedioxythiophene (EDOT) trimer using ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). Phenyl-capped EDOT oligomers were potential candidates for molecular electronics applications and serve as model molecules for PEDOT. By combining UPS, XPS, and NEXAFS, a clear picture of the doping induced changes in the electronic structure of phenyl-capped EDOT-trimer was obtained.

  • 15.
    De, Swati
    et al.
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Kesti, Tero
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Maiti, Manisankar
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Zhang, Fengling
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Inganäs, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics. Linköping University, The Institute of Technology.
    Yartsev, Arkady
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Pascher, Torbjörn
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Sundström, Villy
    Kemisk Fysik, Kemicentrum, Lunds Universitet, Lund, Sweden.
    Exciton Dynamics in Alternating Polyfluorene/Fullerene Blends2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 350, no 1-3, p. 14-22Article in journal (Refereed)
    Abstract [en]

    Exciton dynamics in alternating copolymer/fullerene solar cell blends have been investigated using femtosecond transient absorption spectroscopy. The acceptor concentrations have been varied over a wide range. Experimental data, kinetic modeling and simulations, all indicate that the efficiency of exciton conversion to charges is 100% even at acceptor concentrations as low as 20 wt%. The reported dependence of solar cell efficiency on fullerene concentration may thus arise from other factors. However, there exists an acceptor concentration threshold (5 wt%) below which a substantial fraction of the excitations remain unquenched. The results, we believe are very relevant to optimization of performance efficiency by clever manipulation of morphology. We have also observed exciton–exciton energy transfer in these blends at low acceptor concentrations.

  • 16.
    Doherty, Walter J
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Renouard, T.
    Institut Charles Sadron, UPR 22-CNRS, 6 Rue Boussingault, 67083 Strasbourg Cedex, France, UMR CNRS 6226, Equipe Chimie et In?nierie des Procd´s (CIP), Universit´ de Rennes 1, 263 Avenue du Gnral Leclerc, CS 74205, 35042 Rennes Cedex, France.
    Mathis, C.
    Institut Charles Sadron, UPR 22-CNRS, 6 Rue Boussingault, 67083 Strasbourg Cedex, France.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Electronic structure of Li-intercalated oligopyridines: A comparative study by photoelectron spectroscopy2007In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 126, no 9Article in journal (Refereed)
    Abstract [en]

    The role of nitrogen in the charge transfer and storage capacity of lithium-intercalated heterocyclic oligophenylenes was investigated using photoelectron spectroscopy. The development of new occupied states at low binding energies in the valence band region, as well as core level chemical shifts at both carbon and nitrogen sites, demonstrates partial charge transfer from lithium atoms to the organic component during formation of the intercalated compound. In small compounds, i.e., biphenyl and bipyridine derivatives, the position of the nitrogen heteroatom significantly affects the spacing between gap states in the Li-intercalated film, yet it has minimal effects on the charge storage capacity. In larger, branched systems, the presence of nitrogen in the aromatic system significantly enhances the charge storage capacity while the Li-N bond strength at high intercalation levels is significantly weakened relative to the nitrogen-free derivative. These observations have strong implications towards improved deintercalation processes in organic electrodes in lithium-ion batteries. © 2007 American Institute of Physics.

  • 17.
    Ekström, Ulf
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Carravetta, V.
    Institute of Chemical Physical Processes, CNR, Pisa, Italy.
    Alagia, M.
    Istituto per lo Studio dei Materiali Nanostrutturati, CNR, Roma, Italy and TASC-CNR, Area Science Park, Trieste, Italy.
    Lavollée, M.
    CNRS, Université Paris-Sud, Orsay-Cedex, France.
    Richter, R.
    Sincrotrone Trieste, Trieste, Italy.
    Bolcato, C.
    Dipartimento di Scienze Farmaceutiche, Universitá di Trieste, Trieste, Italy.
    Stranges, S.
    Dipartimento di Chimica and INSTM, Universitá La Sapienza, Roma, Italy.
    The umbrella motion of core-excited CH3 and CD3 methyl radicals2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, no 4, p. 044302-1-044302-11Article in journal (Refereed)
    Abstract [en]

    An accurate experimental and theoretical study of the lowest core excitationof CH3 and CD3 methyl radicals is presented. The complexvibrational structure of the lowest band of the x-ray absorptionspectrum (XAS) is due to the large variation of themolecular geometry, which is planar in the ground state andpyramidal in the core-excited state. The XAS spectra of thetwo radicals were recorded at high resolution and assigned bytheoretical simulations of the spectra, taking into account the couplingof symmetrical stretching and symmetrical bending (umbrellalike) deformations of theradicals. An excellent agreement between experimental and theoretical spectral profilesallowed us to accurately characterize the vibrational structure of theelectronic transition. The similarities, as well as the differences, ofthe peculiar vibrational progression observed for the two radicals areexplained by the strong anharmonicity along the umbrella coordinate andby the isotopic variation, leading to a different probing ofthe double-well potential energy surface of the core excited stateduring the nuclear motion.

  • 18.
    Ektarawong, Annop
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tasnádi, Ferenc
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Wang, Fei
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. 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 thermodynamics2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, no 13, article id 134503Article in journal (Refereed)
    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.

  • 19.
    Engquist, Isak
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lundström, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Liedberg, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Parikh, A.N.
    Pennsylvania State University.
    Allara, D. L.
    Pennsylvania State University.
    Infrared characterization of amorphous and polycrystalline D2O ice on controlled wettability self-assembled alkanethiolate monolayers1997In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 106, no 8, p. 3038-3048Article in journal (Refereed)
    Abstract [en]

    Infrared reflection-absorption spectroscopy has been used to characterize thin overlayers (1-200 Angstrom) of D2O ice deposited in UHV onto a set of self-assembled alkanethiolate monolayers (SAMs) of controlled wettabilities on gold. The SAMs were prepared from a series of controlled composition, mixed solutions of HS(CH2)(15)CH3 and HS(CH2)(16)OH, making it possible to investigate the whole wettability range from theta approximate to 0 degrees to theta=112 degrees, where theta is the static contact angle with water. Dosing of D2O and infrared measurements were carried out at selected sample temperatures between 82 and 150 K. Experimental spectra of ice overlayers recorded below 100 K on all SAM substrates are in good agreement with simulated reflection-absorption spectra, derived from the optical constants of amorphous ice. This agreement allows accurate film thickness determination. In contrast, lack of correspondence in spectral signature is noted between the spectra of annealed films and simulated polycrystalline (or amorphous) ice spectra. We interpret this discrepancy to suggest that significant substrate-induced differences between thin overlayers and bulk ice persist in the latter case. Spectral indications of ice-substrate interaction are also seen for amorphous ice, and are especially prominent in the case of highly hydrophobic (pure CH3-terminated, theta=112 degrees) substrates. In this case the substrate effect extends up to an average film thickness (150-200 Angstrom) corresponding to similar to 50 ice monolayers, in contrast to highly hydrophilic OH-terminated substrate, where the substrate effects appear to vanish beyond similar to 5 monolayers (15-20 Angstrom average thickness). Annealing of thin ice overlayers (2-3 monolayers) clearly demonstrates a strong correlation between the onset as well as progression of the transition from amorphous to polycrystalline ice and the exact substrate wettability or chemical composition. The data further suggest the existence of metastable intermediate forms, that are neither purely amorphous nor polycrystalline. We discuss these observations in terms of substrate-overlayer interaction. A tentative phase diagram summarizing these results is presented. (C) 1997 American Institute of Physics.

  • 20.
    Eriksson, Stefanie
    et al.
    Lund University, Sweden.
    Lasic, Samo
    CR Dev AB, Sweden.
    Nilsson, Markus
    Lund University, Sweden.
    Westin, Carl-Fredrik
    Linköping University, Department of Biomedical Engineering, Medical Informatics. Linköping University, The Institute of Technology. Harvard University, MA 02215 USA.
    Topgaard, Daniel
    Lund University, Sweden.
    NMR diffusion-encoding with axial symmetry and variable anisotropy: Distinguishing between prolate and oblate microscopic diffusion tensors with unknown orientation distribution2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 10, p. 104201-Article in journal (Refereed)
    Abstract [en]

    We introduce a nuclear magnetic resonance method for quantifying the shape of axially symmetric microscopic diffusion tensors in terms of a new diffusion anisotropy metric, D-Delta, which has unique values for oblate, spherical, and prolate tensor shapes. The pulse sequence includes a series of equal-amplitude magnetic field gradient pulse pairs, the directions of which are tailored to give an axially symmetric diffusion-encoding tensor b with variable anisotropy b(Delta). Averaging of data acquired for a range of orientations of the symmetry axis of the tensor b renders the method insensitive to the orientation distribution function of the microscopic diffusion tensors. Proof-of-principle experiments are performed on water in polydomain lyotropic liquid crystals with geometries that give rise to microscopic diffusion tensors with oblate, spherical, and prolate shapes. The method could be useful for characterizing the geometry of fluid-filled compartments in porous solids, soft matter, and biological tissues. (C) 2015 Author(s).

  • 21.
    Fahleson, Tobias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Coriani, Sonia
    University of Trieste, Italy .
    Rizzo, Antonio
    UOS Pisa, Italy .
    Rikken, Geert L J A
    CNRS INSA UJF UPS, France .
    A density functional theory study of magneto-electric Jones birefringence of noble gases, furan homologues, and mono-substituted benzenes2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 139, no 19, p. 194311-Article in journal (Refereed)
    Abstract [en]

    We report on the results of a systematic ab initio study of the Jones birefringence of noble gases, of furan homologues, and of monosubstituted benzenes, in the gas phase, with the aim of analyzing the behavior and the trends within a list of systems of varying size and complexity, and of identifying candidates for a combined experimental/theoretical study of the effect. We resort here to analytic linear and nonlinear response functions in the framework of time-dependent density functional theory. A correlation is made between the observable (the Jones constant) and the atomic radius for noble gases, or the permanent electric dipole and a structure/chemical reactivity descriptor as the para Hammett constant for substituted benzenes.

  • 22.
    Finzel, Kati
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Local conditions for the Pauli potential in order to yield self-consistent electron densities exhibiting proper atomic shell structure2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, no 3, p. 034108-Article in journal (Refereed)
    Abstract [en]

    The local conditions for the Pauli potential that are necessary in order to yield self-consistent electron densities from orbital-free calculations are investigated for approximations that are expressed with the help of a local position variable. It is shown that those local conditions also apply when the Pauli potential is given in terms of the electron density. An explicit formula for the Ne atom is given, preserving the local conditions during the iterative procedure. The resulting orbital-free electron density exhibits proper shell structure behavior and is in close agreement with the Kohn-Sham electron density. This study demonstrates that it is possible to obtain self-consistent orbital-free electron densities with proper atomic shell structure from simple one-point approximations for the Pauli potential at local density level. (C) 2016 AIP Publishing LLC.

  • 23.
    Finzel, Kati
    et al.
    Linköping University, Department of Physics, Chemistry and Biology.
    Martin Pendas, Angel
    University of Oviedo, Spain.
    Francisco, Evelio
    University of Oviedo, Spain.
    Efficient algorithms for Hirshfeld-I charges2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 143, no 8, p. 084115-Article in journal (Refereed)
    Abstract [en]

    A new viewpoint on iterative Hirshfeld charges is presented, whereby the atomic populations obtained from such a scheme are interpreted as such populations which reproduce themselves. This viewpoint yields a self-consistent requirement for the Hirshfeld-I populations rather than being understood as the result of an iterative procedure. Based on this self-consistent requirement, much faster algorithms for Hirshfeld-I charges have been developed. In addition, new atomic reference densities for the Hirshfeld-I procedure are presented. The proposed reference densities are N-representable, display proper atomic shell structure and can be computed for any charged species.

  • 24.
    Fransson, Thomas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Coriani, Sonia
    University of Trieste, Italy .
    Christiansen, Ove
    Aarhus University, Denmark .
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Carbon X-ray absorption spectra of fluoroethenes and acetone: A study at the coupled cluster, density functional, and static-exchange levels of theory2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 138, no 12Article in journal (Refereed)
    Abstract [en]

    Near carbon K-edge X-ray absorption fine structure spectra of a series of fluorine-substituted ethenes and acetone have been studied using coupled cluster and density functional theory (DFT) polarization propagator methods, as well as the static-exchange (STEX) approach. With the complex polarization propagator (CPP) implemented in coupled cluster theory, relaxation effects following the excitation of core electrons are accounted for in terms of electron correlation, enabling a systematic convergence of these effects with respect to electron excitations in the cluster operator. Coupled cluster results have been used as benchmarks for the assessment of propagator methods in DFT as well as the state-specific static-exchange approach. Calculations on ethene and 1,1-difluoroethene illustrate the possibility of using nonrelativistic coupled cluster singles and doubles (CCSD) with additional effects of electron correlation and relativity added as scalar shifts in energetics. It has been demonstrated that CPP spectra obtained with coupled cluster singles and approximate doubles (CC2), CCSD, and DFT (with a Coulomb attenuated exchange-correlation functional) yield excellent predictions of chemical shifts for vinylfluoride, 1,1-difluoroethene, trifluoroethene, as well as good spectral features for acetone in the case of CCSD and DFT. Following this, CPP-DFT is considered to be a viable option for the calculation of X-ray absorption spectra of larger pi-conjugated systems, and CC2 is deemed applicable for chemical shifts but not for studies of fine structure features. The CCSD method as well as the more approximate CC2 method are shown to yield spectral features relating to pi*-resonances in good agreement with experiment, not only for the aforementioned molecules but also for ethene, cis-1,2-difluoroethene, and tetrafluoroethene. The STEX approach is shown to underestimate pi*-peak separations due to spectral compressions, a characteristic which is inherent to this method.

  • 25.
    Friedlein, Rainer
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Crispin, Xavier
    Linköping University, The Institute of Technology. Linköping University, Department of Science and Technology.
    Suess, C.
    Pickholz, M.
    Center for Molecular Modeling, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    The role of intermolecular polarization for the stability of lithium intercalation compounds of a- and ß-perylene2004In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 5, p. 2239-2245Article in journal (Refereed)
    Abstract [en]

    The charge transfer in Li-intercalation compounds of the polyaromatic hydrocarbon perylene was examined. It was found that the valence and core-level photoelectron spectroscopies characterized the bonding configuration of the alkali metal atoms. The effect of intermolecular polarization on the ionization potential of Li atoms was compensated by a screening of the Madelung energy. The data collected illustrated that the large charge transfer in the a-perylene was due to the lower ionization potential of lithium atoms.

  • 26. Gisslen, L.
    et al.
    Johansson, Agneta
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Molecular genetics .
    Stafström, Sven
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Charge and energy dynamics in photo-excited poly(para-phenylenevinylene) systems2004In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 121, no 3, p. 1601-1608Article in journal (Refereed)
    Abstract [en]

    The results from simulations of charge and energy dynamics in poly(para-phenylenevinylene) (PPV) and PPV interacting with C60 were reported. The time-dependent Schrödinger equation and the lattice equation of motion simultaneously and nonadiabatically solved for performing these simulations. The electronic system and the coupling of the electrons to the lattice were described by an extended three-dimensional version of the Su-Schrieffer-Heeger model. The simulation of electron and lattice dynamics following an electronic excitations at different energies was also presented. The results show that both exciton diffusion and transitions from high to lower lying excitations were stimulated by increasing the lattice energy.

  • 27. Greczynski, G.
    et al.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Experimental study of poly(9,9-dioctyl-fluorene) and its interfaces with Li, Al, and LiF2000In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 113, no 6, p. 2407-2412Article in journal (Refereed)
    Abstract [en]

    The interaction of poly(9,9-dioctyl-fluorene) (PFO) films with Li, Al and LiF substrates was investigated by X-ray and ultraviolet photoelectron spectroscopy. The chemical and electronic structure of the interfaces were examined. The Li/PFO, LiF/PFO, LiF/Al, Al/OFO and Al/LiF/PFO interfaces were compared using Alq3.

  • 28. Greczynski, G.
    et al.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Hybrid interfaces of poly(9,9-dioctylfluorene) employing thin insulating layers of CsF: A photoelectron spectroscopy study2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 114, no 19, p. 8628-8636Article in journal (Refereed)
    Abstract [en]

    A number of sandwich-type interfaces were studied using x-ray and ultraviolet photoelectron spectroscopy including CsF/PFO/ Al/CsF/PFO, Al/CsF/Au, CsF/Al, CsF/AlxOy, and CsF/Au. The results indicate that the presence of aluminum is essential for dissociation.

  • 29. Greczynski, G.
    et al.
    Fahlman, Mats
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Johansson, N.
    Dos, Santos D.A.
    Dos Santos, D.A., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Dkhissi, A.
    Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Electronic structure of poly(9,9-dioctylfluorene) in the pristine and reduced state2002In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 116, no 4, p. 1700-1706Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a polymer of interest in polymer-based light emitting devices, poly(9,9-dioctyl-fluorene), was studied using a combined experimental-theoretical approach. Results were compared with those of equivalent studies of the electronic structure of two related conjugated polymers: poly(p-phenylene) and a latter-type poly (p-phenylene) (LPPP). Finally, it was shown that electrons added to the polymer system lead to the formation of polarons at low doping levels, and bipolarons at high doping levels. The energies of the polaron and bipolaron states were measured directly, and agree with the theoretical modeling of the added electrons.

  • 30. Greczynski, G.
    et al.
    Johansson, N.
    Logdlund, M.
    Lögdlund, M., ACREO AB, S-602 21 Norrköping, Sweden.
    Pettersson, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Horsburgh, L.E.
    Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
    Monkman, A.P.
    Department of Physics, University of Durham, South Road, Durham DH1 3LE, United Kingdom.
    Dos, Santos D.A.
    Dos Santos, D.A., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Bredas, J.L.
    Brédas, J.L., Service de Chimie des Matériaux Nouveaux, Centre de Recherche en Electronique et Photonique Moléculaires, Université de Mons-Hainaut, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, 1306 E. University Blvd., Tucson, AZ 85721-0041, United States.
    Electronic structure of pristine and sodium doped poly(p-pyridine)2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 114, no 9, p. 4243-4252Article in journal (Refereed)
    Abstract [en]

    Ultraviolet spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS) were used to study the valence electronic structures of pristine and sodium doped poly (p-pyridine) (PPY). The UPS spectra were analyzed by studying the density-of-valence-states (DOVS) derived from quantum chemical calculations. The electronic band structure of the PPY chains was also theoretically investigated using the valence effective Hamiltonian (VEH) method. The theoretical approach was found to be more accurate in describing the electronic structure of PPY.

  • 31.
    Guo, J.-H.
    et al.
    Uppsala University.
    Magnuson, Martin
    Uppsala University.
    Såthe, C.
    Uppsala University.
    Nordgren, J.
    Uppsala University.
    Yang, L.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Luo, Y.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Ågren, H.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Xing, K. Z.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Johansson, N.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry . Linköping University, The Institute of Technology.
    Daik, R.
    Durham University.
    Feast, W. J.
    Durham University.
    Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s1998In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 108, no 14, p. 5990-5996Article in journal (Refereed)
    Abstract [en]

    The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.

  • 32.
    Hao, Feng
    et al.
    Sandia National Laboratories, Albuquerque, New Mexico, USA.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, The Institute of Technology.
    Mattsson, Ann E.
    Sandia National Laboratories, Albuquerque, New Mexico, USA.
    Using the electron localization function to correct for confinement physics in semi-local density functional theory2014In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 140, no 18, article id 18A536Article in journal (Refereed)
    Abstract [en]

    We have previously proposed that further improved functionals for density functional theory can be constructed based on the Armiento-Mattsson subsystem functional scheme if, in addition to the uniform electron gas and surface models used in the Armiento-Mattsson 2005 functional, a model for the strongly confined electron gas is also added. However, of central importance for this scheme is an index that identifies regions in space where the correction provided by the confined electron gas should be applied. The electron localization function (ELF) is a well-known indicator of strongly localized electrons. We use a model of a confined electron gas based on the harmonic oscillator to show that regions with high ELF directly coincide with regions where common exchange energy functionals have large errors. This suggests that the harmonic oscillator model together with an index based on the ELF provides the crucial ingredients for future improved semi-local functionals. For a practical illustration of how the proposed scheme is intended to work for a physical system we discuss monoclinic cupric oxide, CuO. A thorough discussion of this system leads us to promote the cell geometry of CuO as a useful benchmark for future semi-local functionals. Very high ELF values are found in a shell around the O ions, and take its maximum value along the Cu–O directions. An estimate of the exchange functional error from the effect of electron confinement in these regions suggests a magnitude and sign that could account for the error in cell geometry.

  • 33.
    Herberthson, Magnus
    et al.
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Özarslan, Evren
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering.
    Knutsson, Hans
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Linköping University, Center for Medical Image Science and Visualization (CMIV).
    Westin, Carl-Fredrik
    Linköping University, Department of Biomedical Engineering, Division of Biomedical Engineering. Linköping University, Faculty of Science & Engineering. Harvard Medical Sch, MA 02215 USA.
    Dynamics of local magnetization in the eigenbasis of the Bloch-Torrey operator2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 12, article id 124201Article in journal (Refereed)
    Abstract [en]

    We consider diffusion within pores with general shapes in the presence of spatially linear magnetic field profiles. The evolution of local magnetization of the spin bearing particles can be described by the Bloch-Torrey equation. We study the diffusive process in the eigenbasis of the non-Hermitian Bloch-Torrey operator. It is possible to find expressions for some special temporal gradient waveforms employed to sensitize the nuclear magnetic resonance (NMR) signal to diffusion. For more general gradient waveforms, we derive an efficient numerical solution by introducing a novel matrix formalism. Compared to previous methods, this new approach requires a fewer number of eigenfunctions to achieve the same accuracy. This shows that these basis functions are better suited to the problem studied. The new framework could provide new important insights into the fundamentals of diffusion sensitization, which could further the development of the field of NMR. Published by AIP Publishing.

  • 34.
    Holmgaard List, Nanna
    et al.
    University of Southern Denmark, Denmark.
    Kauczor, Joanna
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Saue, Trond
    University of Toulouse 3, France.
    Jorgen Aagaard Jensen, Hans
    University of Southern Denmark, Denmark.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Chemistry. Linköping University, Faculty of Science & Engineering.
    Beyond the electric-dipole approximation: A formulation and implementation of molecular response theory for the description of absorption of electromagnetic field radiation2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 24, p. 244111-Article in journal (Refereed)
    Abstract [en]

    We present a formulation of molecular response theory for the description of a quantum mechanical molecular system in the presence of a weak, monochromatic, linearly polarized electromagnetic field without introducing truncated multipolar expansions. The presentation focuses on a description of linear absorption by adopting the energy-loss approach in combination with the complex polarization propagator formulation of response theory. Going beyond the electric-dipole approximation is essential whenever studying electric-dipole-forbidden transitions, and in general, non-dipolar effects become increasingly important when addressing spectroscopies involving higher-energy photons. These two aspects are examined by our study of the near K-edge X-ray absorption fine structure of the alkaline earth metals (Mg, Ca, Sr, Ba, and Ra) as well as the trans-polyenes. In following the series of alkaline earth metals, the sizes of non-dipolar effects are probed with respect to increasing photon energies and a detailed assessment of results is made in terms of studying the pertinent transition electron densities and in particular their spatial extension in comparison with the photon wavelength. Along the series of trans-polyenes, the sizes of non-dipolar effects are probed for X-ray spectroscopies on organic molecules with respect to the spatial extension of the chromophore.

  • 35.
    Imam, Mewlude
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ERIC, Sweden.
    Höglund, Carina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ERIC, Sweden.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. European Spallat Source ERIC, Sweden; IHI Ionbond AG, Switzerland.
    Hall-Wilton, Richard
    European Spallat Source ERIC, Sweden; Mid Sweden Univ, Sweden.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pedersen, Henrik
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Plasma CVD of hydrogenated boron-carbon thin films from triethylboron2018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 148, no 3, article id 034701Article in journal (Refereed)
    Abstract [en]

    Low-temperature chemical vapor deposition (CVD) of B-C thin films is of importance for neutron voltaics and semiconductor technology. The highly reactive trialkylboranes, with alkyl groups of 1-4 carbon atoms, are a class of precursors that have been less explored for low-temperature CVD of B-C films. Herein, we demonstrate plasma CVD of B-C thin films using triethylboron (TEB) as a single source precursor in an Ar plasma. We show that the film density and B/C ratio increases with increasing plasma power, reaching a density of 2.20 g/cm(3) and B/C = 1.7. This is attributed to a more intense energetic bombardment during deposition and more complete dissociation of the TEB molecule in the plasma at higher plasma power. The hydrogen content in the films ranges between 14 and 20 at. %. Optical emission spectroscopy of the plasma shows that BH, CH, C-2, and H are the optically active plasma species from TEB. We suggest a plasma chemical model based on beta-hydrogen elimination of C2H4 to form BH3, in which BH3 and C2H4 are then dehydrogenated to form BH and C2H2. Furthermore, C2H2 decomposes in the plasma to produce C-2 and CH, which together with BH and possibly BH3-x(C2H5)(x) are the film forming species. (c) 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution ( CC BY) license (http://creativecommons.org/licenses/by/4.0/).

  • 36.
    Jakobsson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    A Monte Carlo study of charge transfer in DNA2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 129, no 12, p. 125102-Article in journal (Refereed)
    Abstract [en]

    A model describing charge (hole) transport in DNA has been developed. The individual charge transfer steps in the transport process are described by Marcus theory modified to account for electron delocalization over adjacent identical nucleobases. Such a modification, as well as introducing a distance dependence in the reorganization energy, is necessary in order to reach an agreement with the observed transfer rates in well defined model systems to DNA. Using previously published results as a reference for the reorganization energy and with the delocalization described within the Hückel model we obtain an excellent agreement with experimental data.

  • 37.
    Jakobsson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Linares, Mathieu
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Monte Carlo simulations of charge transport in organic systems with true off-diagonal disorder2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, no 11Article in journal (Refereed)
    Abstract [en]

    In this work, a novel method to model off-diagonal disorder in organic materials has been developed. The off-diagonal disorder is taken directly from the geometry of the system, which includes both a distance and an orientational dependence on the constituent molecules, and does not rely on a parametric random distribution. To study this method, a system is generated by running molecular dynamics simulations on phenylene-vinylene oligomers packed into boxes. The impact of the model is then investigated by means of Monte Carlo simulations of the charge transport in these boxes and a comparison is made to the commonly used model of off-diagonal disorder, where only the distance dependence is properly accounted for. It is shown that this new model has a significant impact on the charge transport, while still being compliant with previously published and confirmed results.

  • 38.
    Jakobsson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Hole mobility and transport mechanisms in lambda-DNA2009In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 15, p. 155102-Article in journal (Refereed)
    Abstract [en]

    We have performed a study of charge transport in lambda-DNA using a recently developed model based on Marcus theory and dynamic Monte Carlo simulations. The model accounts for charge delocalization over multiple adjacent identical nucleobases. Such delocalized states are found to act as traps for charge transport and therefore have a negative impact on the charge carrier (hole) mobility. Both the electric field and temperature dependence of the mobility in lambda-DNA is reported in this paper. Furthermore, the detailed information produced by the simulation allow us to plot the progress of a hole propagating through the DNA sequence and this is used to identify the bottlenecks that limits the charge transport process.

  • 39.
    Jakobsson, Mattias
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Polaron effects and electric field dependence of the charge carrier mobility in conjugated polymers2011In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 135, no 13, p. 134902-Article in journal (Refereed)
    Abstract [en]

    Charge transport in conjugated polymers has been investigated using Monte Carlo simulations implemented on top of the Marcus theory for donor-acceptor transition rates. In particular, polaron effects and the dependency of the mobility on the temperature and the applied electric field have been studied. The conclusions are that while the qualitative temperature dependence is similar to that predicted by Miller-Abrahams theory in the Gaussian disorder model (GDM), the electric field dependence is characterized by a crossover into the Marcus inverted region, not present in the GDM. Furthermore, available analytical approximations to describe the electric field dependence of the mobility in Marcus theory fail to fit the simulation data and hence cannot be used to directly draw conclusions about the importance of polaron effects for charge transport in conjugated polymers.

  • 40.
    Jansson, Emil
    et al.
    Royal Institute of Technology.
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Minaev, Boris
    Royal Institute of Technology.
    Ågren, Hans
    Royal Institute of Technology.
    Evaluation of low-scaling methods for calculation of phosphorescence parameters2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 124, p. 114106-1-114106-7Article in journal (Refereed)
    Abstract [en]

      

  • 41.
    Jiemchooroj, Auayporn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Ekström, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Near-edge X-ray absorption and natural circular dichroism spectra of L-alanine: a theoretical study based on the complex polarization propagator approach2007In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 16, p. 165104-Article in journal (Refereed)
    Abstract [en]

    The complex polarization propagator method [J. Chem. Phys. 123, 194103 (2005)] has been employed in conjunction with density functional theory and gauge-including atomic orbitals in order to determine the near-edge x-ray absorption and natural circular dichroism spectra of L-alanine in its neutral and zwitterionic forms. Results are presented for the K-edges of carbon, nitrogen, and oxygen. In contrast to traditional methods, the proposed approach enables a direct determination ofspectra at an arbitrary frequency instead of focusing on the rotatory strengths for individual electronic transitions. The propagator includes a complete set ofand allows for full core-hole relaxation. The theoretical spectrum at the nitrogen K-edge of the zwitterion compares well with the experimental spectrum. the nonredundant electron-transfer operators

  • 42.
    Jiemchooroj, Auayporn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics . Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics . Linköping University, The Institute of Technology.
    Electronic circular dichroism spectra from the complex polarization propagator2007In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 126, no 13, p. 134102-Article in journal (Refereed)
    Abstract [en]

    The complex linear polarization propagator approach has been applied to the calculation of electronic circular dichroism spectra of 3R-chloro-1-butyne, 3R-methylcyclopentanone, 3S-methylcyclohexanone, 4R-1,1-dimethyl-[3]-(1,2)ferrocenophan-2-on, S-3,3,3,3-tetramethyl-1,1-spirobi[3H,2,1]-benzoxaselenole, and the fullerene C84. Using time-dependent Kohn-Sham density functional theory, it is shown that a direct and efficient evaluation of the circular dichroism spectrum can be achieved. The approach allows for the determination of the circular dichroism at an arbitrary wavelength thereby, in a common formulation and implementation, covering the visible, ultraviolet, and x-ray regions of the spectrum. In contrast to traditional methods, the entire manifold of excited states is taken into account in the calculation of the circular dichroism at a given wavelength

  • 43.
    Jiemchooroj, Auayporn
    et al.
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics .
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    X-ray absorption and natural circular dichroism spectra of C84: A theoretical study using the complex polarization propagator approach2008In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 128, no 23Article in journal (Refereed)
    Abstract [en]

    The x-ray absorption and circular dichroism K -edge spectra for the D2 -isomer of C84 have been determined using the complex polarization propagator method in conjunction with Kohn-Sham density functional theory. The circular dichroism spectrum is rich in details and, in comparison to the absorption spectrum, it provides a superior resolution of the electronic transitions below the ionization threshold. © 2008 American Institute of Physics.

  • 44.
    Johansson, N.
    et al.
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Osada, T.
    Sumitomo Chem Co Ltd, Japan.
    Stafström, Sven
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Salaneck, William R.
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, The Institute of Technology.
    Parente, V.
    Mons University, Belgium.
    dos Santos, D. A.
    Mons University, Belgium.
    Crispin, Xavier
    Mons University, Belgium.
    Bredas, J. L.
    Mons University, Belgium.
    Electronic structure of tris(8-hydroxyquinoline) aluminum thin films in the pristine and reduced states1999In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 111, no 5, p. 2157-2163Article in journal (Refereed)
    Abstract [en]

    The electronic structure of tris(8-hydroxyquinoline) aluminum (Alq(3)) has been studied in the pristine molecular solid state as well as upon interaction (doping) with potassium and lithium. We discuss the results of a joint theoretical and experimental investigation, based on a combination of x-ray and ultraviolet photoelectron spectroscopies with quantum-chemical calculations at the density functional theory level. Upon doping, each electron transferred from an alkali metal atom is stored on one of the three ligands of the Alq(3) molecule, resulting in a new spectral feature (peak) in the valence band that evolves uniformly when going from a doping level of one to three metal atoms per Alq(3) molecule. (C) 1999 American Institute of Physics. [S0021-9606(99)50628-4].

  • 45. Jonsson, D.
    et al.
    Norman, Patrick
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Computational Physics .
    Agren, H.
    Ågren, H., Theoretical Chemistry, Royal Institute of Technology, Teknikringen 30, S-10044, Stockholm, Sweden.
    Rizzo, A.
    Istituto di Chimica Quantistica ed Energetica Molecolare del Consiglio Nazionale delle Ricerche, Area Della Ricerca di Pisa, Loc. San Cataldo, Via G. Moruzzi 1, I-56124 Pisa, Italy.
    Coriani, S.
    Dipartimento di Scienze Chimiche, Università degli Studi di Trieste, via Licio Giorgieri 1, I-34127 Trieste, Italy.
    Ruud, K.
    San Diego Supercomputer Center, San Diego, CA 92039-0505, United States.
    The Cotton-Mouton effect of gaseous CO2, N2O, OCS and CS2. A cubic response multiconfigurational self-consistent field study2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 114, no 19, p. 8372-8381Article in journal (Refereed)
    Abstract [en]

    An extended ab initio study of the Cotton-Mouton effect of CO2, N2O, OCS, and CS2, employing correlated wave functions expanded in correlation consistent basis sets as large as t-aug-cc-pVTZ and an analytic response approach was carried out. The dependence of the static diamagnetic and paramagnetic hypermagnetizabilities at the SCF level was analyzed. Results of the study are the best possible with current state-of-the-art theoretical and computational methods.

  • 46.
    Kauczor, Joanna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Christiansen, Ove
    Aarhus University, Denmark .
    Coriani, Sonia
    University of Trieste, Italy .
    Communication: A reduced-space algorithm for the solution of the complex linear response equations used in coupled cluster damped response theory2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 139, no 21, p. 211102-Article in journal (Refereed)
    Abstract [en]

    We present a reduced-space algorithm for solving the complex (damped) linear response equations required to compute the complex linear response function for the hierarchy of methods: coupled cluster singles, coupled cluster singles and iterative approximate doubles, and coupled cluster singles and doubles. The solver is the keystone element for the development of damped coupled cluster response methods for linear and nonlinear effects in resonant frequency regions.

  • 47.
    Kauczor, Joanna
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Norman, Patrick
    Linköping University, Department of Physics, Chemistry and Biology, Computational Physics. Linköping University, The Institute of Technology.
    Saidi, Wissam A
    University of Pittsburgh, PA USA .
    Non-additivity of polarizabilities and van der Waals C-6 coefficients of fullerenes2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 138, no 11Article in journal (Refereed)
    Abstract [en]

    We present frequency-dependent polarizabilities and C-6 dipole-dipole dispersion coefficients for a wide range of fullerene molecules including C-60, C-70, C-78, C-80, C-82, and C-84. The static and dynamic polarizabilities at imaginary frequencies are computed using time-dependent Hartree-Fock, B3LYP, and CAM-B3LYP ab initio methods by employing the complex linear polarization propagator and are subsequently utilized to determine the C-6 coefficients using the Casimir-Polder relation. Overall, the C60 and C70 average static polarizabilities alpha(0) agree to better than 2% with linear-response coupledcluster single double and experimental benchmark results, and the C-6 coefficient of C-60 agrees to better than 1% with the best accepted value. B3LYP provides the best agreement with benchmark results with deviations less than 0.1% in alpha(0) and C-6. We find that the static polarizabilities and the C-6 coefficients are non-additive, and scale, respectively, as N1.2 and N2.2 with the number of carbon atoms in the fullerene molecule. The exponent for C-6 power-dependence on N is much smaller than the value predicted recently based on a classical-metallic spherical-shell approximation of the fullerenes.

  • 48. Keil, M.
    et al.
    Samori, P.
    Samorí, P., Department of Physics, Humboldt University Berlin, Invalidenstrasse 110, D-10115 Berlin, Germany.
    Dos, Santos D.A.
    Dos Santos, D.A., Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Birgerson, J.
    Friedlein, Rainer
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    Dkhissi, A.
    Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium.
    Watson, M.
    Max-Planck-Institut for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
    Mullen, K.
    Müllen, K., Max-Planck-Institut for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
    Bredas, J.L.
    Brédas, J.L., Université de Mons-Hainaut, Place du Parc 20, B-7000 Mons, Belgium, Department of Chemistry, University of Arizona, Tucson, AZ 85721, United States.
    Rabe, J.P.
    Department of Physics, Humboldt University Berlin, Invalidenstrasse 110, D-10115 Berlin, Germany.
    Salaneck, William R
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry .
    High levels of alkali-metal storage in thin films of hexa-peri-hexabenzocoronene2002In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 116, no 24, p. 10854-10860Article in journal (Refereed)
    Abstract [en]

    The results of the doping of molecular solid films of the medium-sized aromatic hydrocarbon hexa-peri-hexabenzocoronene (HBC), using lithium or sodium atoms were presented. The evolution of the valence band electronic structure was monitored by x-ray photoelectron spectroscopy and studied by ultraviolet photoelectron spectroscopy. Results indicated that n-doping depended on the type of alkali-metal atom employed and on the molecular order of the film. The smaller Li ion was found to have a stronger influence on the electronic structure than Na ions. These results revealed the potential use of the graphene materials in lithium-ion batteries with a high charge-storage capacity.

  • 49. KNUTS, SÖREN
    et al.
    OJAMAE, LARS
    HERMANSSON, KERSTI
    Uppsala universitet, Kemiska institutionen.
    AN AB-INITIO STUDY OF THE OH STRETCHING FREQUENCIES IN ICE-II, ICE-VIII, AND ICE-IX1993In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 99, no 4, p. 2917-2928Article in journal (Refereed)
    Abstract [en]

    Ab initio studies of the uncoupled, anharmonic OH and OD stretching frequency shifts in the three proton-ordered ice phases known, ice II, ice VIII, and ice IX, are presented. The ice structures are simulated by (H2O)5 supermolecules surrounded by point charges representing the correct crystal potentials. The calculations include electron correlation at the MP2 (DZP) level. For the eight different OH (OD) vibrators studied, the crystal environment leads to a downshift of the anharmonic OD frequency in the range 195-265 cm-1, in good agreement with experimental values (222-281 cm-1) when corrections are made for the limited supermolecular size (approximately - 45 cm-1), and, for ice VIII, also for the effects of the nonhydrogen bonded network (approximately + 75 cm- 1). Also the agreement between absolute experimental and theoretical OD frequencies is good when errors due to basis set limitation (approximately - 75 cm-1 ) are taken into account. The calculations suggest a reassignment of two of the experimental OD bands in ice II and all three experimental OD bands in ice IX. Calculations for charge-embedded (H2O)9 and (H2O)13 ice clusters show that at least a nonamer is needed to avoid boundary effects from the size of the supermolecule. Theoretical correlation curves between H-bond parameters-R (O ... 0), nu(OH), r(e)(OH), and infrared absorption intensity-are presented for the three ice phases and are compared to liquid water computations.

  • 50.
    Kuo, Jer-Lai
    et al.
    Department of Chemistry, Ohio State University, Columbus, Ohio 43214.
    Coe, James V.
    Department of Chemistry, Ohio State University, Columbus, Ohio 43214.
    Singer, Sherwin J.
    Department of Chemistry, Ohio State University, Columbus, Ohio 43214.
    Band, Yehuda B.
    Departments of Chemistry and Physics, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
    Ojamäe, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry .
    On the use of graph invariants for efficiently generating hydrogen bond topologies and predicting physical properties of water clusters and ice2001In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 114, no 6, p. 2527-2540Article in journal (Refereed)
    Abstract [en]

    Water clusters and some phases of ice are characterized by many isomers with similar oxygen positions, but which differ in direction of hydrogen bonds. A relationship between physical properties, like energy or magnitude of the dipole moment, and hydrogen bond arrangements has long been conjectured. The topology of the hydrogen bond network can be summarized by oriented graphs. Since scalar physical properties like the energy are invariant to symmetry operations, graphical invariants are the proper features of the hydrogen bond network which can be used to discover the correlation with physical properties. We demonstrate how graph invariants are generated and illustrate some of their formal properties. It is shown that invariants can be used to change the enumeration of symmetry-distinct hydrogen bond topologies, nominally a task whose computational cost scales like N2, where N is the number of configurations, into an N ln N process. The utility of graph invariants is confirmed by considering two water clusters, the (H2O)6 cage and (H2O)20 dodecahedron, which, respectively, possess 27 and 30 026 symmetry-distinct hydrogen bond topologies associated with roughly the same oxygen atom arrangements. Physical properties of these clusters are successfully fit to a handful of graph invariants. Using a small number of isomers as a training set, the energy of other isomers of the (H2O)20 dodecahedron can even be estimated well enough to locate phase transitions. Some preliminary results for unit cells of ice-Ih are given to illustrate the application of our results to periodic systems.

     

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