Publications

2017

  1. David Reith, Mikael Christensen, Walter Wolf, Volker Eyert, Erich Wimmer, Georg Schmitz, Ralph Altenfeld, Markus Apel, Gottfried Laschet, Bernd Böttger
    ICME 2017
    doi:
    The origin of most materials properties is rooted in the atomic scale. A detailed microscopic understanding of the physics and chemistry is thus mandatory for successful computational materials engineering. The MedeA computational environment provides a very efficient tool to perform atomistic...

2015

  1. CIO Review
    doi:
    Despite the downturn and reduced traction in export market, the U.S. chemical industry is fast picking pace. The chemical sector is now spiraling towards a sustained global expansion that will result in increased trade. This year, the maximum traction in chemical was observed in the automotive...
  2. James F Brazdil, Mark A Toft, Sean S Y Lin, Stephen T McKenna, Gerry Zajac, James A Kaduk, and Joseph T Golab.
    ApplCatA, 2015 vol. 495 pp. 115-123.
    Acrylonitrile is a major chemical intermediate used in the production of a wide range of chemical and polymer products. Central to the commercial process is a proprietary catalyst consisting of a complex mixture of metal oxides containing a bismuth-containing molybdate phase that is active and...
  3. Mikael Christensen, Walter Wolf, Clive Freeman, Erich Wimmer, RB Adamson, L Hallstadius, PE Cantonwine, EV Mader
    Journal of Nuclear Materials 460: 82–96.(2015)
    Diffusion of point defects, nucleation of dislocation loops, and the associated dimensional changes of pure and H-loaded hcp-Zr have been investigated by a combination of ab initio calculations and classical simulations. Vacancy diffusion is computed to be anisotropic with Dvac,basal = 8.6

2014

  1. Mikael Christensen, Walter Wolf, Clive M Freeman, Erich Wimmer, R B Adamson, L Hallstadius, P E Cantonwine, and E V Mader
    Journal of Nuclear Materials 445, no. 1: 241–250. (2014)
    The effect of the alloying elements Sn, Fe, Cr, Ni, Nb, and O on hydrogen-containing alpha-zirconium and zirconium hydrides is investigated using ab initio quantum mechanical calculations and classical simulations. Cr, Fe, and Ni atoms attract interstitially dissolved H atoms whereas interstitial...
  2. H. N. Sharma, V. Sharma, T. Hamzehlouyan, W. Epling, A. B. Mhadeshwar, and R. Ramprasad
    J. Phys. Chem. C, 118 (13), 6934 (2014)
    This work examines the complex nature of SOₓ (x = 0–4) interaction and oxidation on Pt(111) and Pd(111) surfaces using density functional theory (DFT) calculations coupled with microkinetic modeling. Thermodynamic and kinetic analyses suggest similar adsorption and oxidation behaviors for SOx...
  3. Arthur France-Lanord, Dave Rigby, Alex Mavromaras, Volker Eyert, Paul Saxe, Clive Freeman, Erich Wimmer
    15th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE), 2014
    Results of atomic-scale simulations are presented including thermal conductivity, elastic moduli, diffusion, and adhesion. These types of simulations are most conveniently performed with the MedeA computational environment, which comprises experimental structure databases together with building...
  4. Xavier Rozanska, James J P Stewart, Philippe Ungerer, Benoit Leblanc, Clive Freeman, Paul Saxe, and Erich Wimmer.
    J Chem Eng Data, 2014 p. 140603143218005.
    The atomistic and molecular simulation environment [MedeA](/medea) in its functionalities and graphical user interface has been enhanced to prepare and submit on the order of 1000 simulations on different structures, and to collect and help in the analysis of the results. We illustrate this with...
  5. R Asahi, C M Freeman, P Saxe, and E Wimmer
    Modelling Simul. Mater. Sci. Eng. 22, 075009 (2014)
    This work shows a straightforward procedure to derive forcefields (FFs) which are able to describe the structural, thermal and transport properties of condensed phases. The approach is based on ab initio molecular dynamics trajectories and an empirical calibration such as the melting point. This is...
  6. A Wimmer, M Smolka, W Heinz, T Detzel, W Robl, C Motz, Volker Eyert, Erich Wimmer, F Jahnel, R Treichler, G Dehm
    Materials Science & Engineering A 618 (2014) 398-405
    Smaller grain sizes are known to improve the strength and ductility of metals by the Hall–Petch effect. Consequently, metallic thin films and structures which must sustain mechanical loads in service are deposited under processing conditions that lead to a fine grain size. In this study, we reveal...
  7. Fernando L Dri, ShunLi Shang, Louis G Hector Jr., Paul Saxe, Zi-Kui Liu, Robert J Moon, and Pablo D Zavattieri
    Modelling and Simulation in Materials Science and Engineering, 2014 vol. 22 (8) p. 085012.
    doi:
    Anisotropy and temperature dependence of structural, thermodynamic and elastic properties of crystalline cellulose Iβ were computed with first-principles density functional theory (DFT) and a semi-empirical correction for van der Waals interactions. Specifically, we report the computed temperature...
  8. X Rozanska, P Ungerer, B Leblanc, P Saxe, and E Wimmer
    Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles Dec (2014)
    This work demonstrates the systematic prediction of thermodynamic properties for batches of thousands of molecules using automated procedures.

2013

  1. J S McCloy, Walter Wolf, Erich Wimmer, and B J Zelinski
    Journal of Applied Physics, 113(2), 023706–023706–7.(2013)
    The lattice parameter of cubic chemical vapor deposited (CVD) ZnS with measured oxygen concentrations <0.6 at. % and hydrogen impurities of <0.015 at. % has been measured and found to vary between −0.10% and +0.09% relative to the reference lattice parameter (5.4093 Å) of oxygen-free cubic...
  2. MC Gao, Y Suzuki, Hannes Schweiger, ÖN Doğan, J Hawk, M Widom
    Journal of Physics: Condensed Matter, 25(7), 075402 (2013)
    V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and...
  3. Xavier Rozanska, Philippe Ungerer, Benoît Leblanc, and Marianna Yiannourakou
    Oil & Gas Science and Technology – Revue d’IFP Energies Nouvelles.
    We use periodic Density Functional Theory (DFT) method to generate the electrostatic potentials of adsorption materials and use them in Grand Canonical Monte Carlo simulations of fluid adsorption isotherms. This permits us to consider complex solids showing defects and without a priori knowledge of...
  4. Mikael Christensen, Volker Eyert, Clive M Freeman, Erich Wimmer, A Jain, J Blatchford, D Riley, and J Shaw
    Journal of Applied Physics 114, no. 3: 033533. (2013)
    The formation of Ni(Pt)silicides on a Si(001) surface is investigated using an ab initio approach. After deposition of a Ni overlayer alloyed with Pt, the calculations reveal fast diffusion of Ni atoms into the Si lattice, which leads initially to the formation of Ni₂Si. At the same time, Si atoms...
  5. P Soukiassian, E Wimmer, E Celasco, C Giallombardo, S Bonanni, L Vattuone, L Savio, A Tejeda, M Silly, M D’angelo, F Sirotti, and M Rocca
    Nature Communications 4, 2800 (2013)
    One of the key steps in nanotechnology is our ability to engineer and fabricate low-dimensional nano-objects, such as quantum dots, nanowires, two-dimensional atomic layers or three-dimensional nano-porous systems. Here we report evidence of nanotunnel opening within the subsurface region of a wide...
  6. Marianna Yiannourakou, Philippe Ungerer, Benoît Leblanc, N Ferrando and JM Teuler
    Mol. Sim. 39, 1165 (2013)
    This paper illustrates the use of Monte Carlo (MC) simulations to study a wide range of systems of interest for biomass conversion into high-added value chemicals and biofuels. The interest is focused on the use of molecular simulation to predict the physical–chemical properties of pure compounds...
  7. Marianna Yiannourakou, Philippe Ungerer, Benoît Leblanc, Xavier Rozanska, Paul Saxe, S Vidal-Gilbert, F Gouth, and F Montel
    Oil & Gas Science and Technology – Revue d’IFP Energies Nouvelles
    Molecular Simulation of Adsorption in Microporous Materials — The development of industrial software, the decreasing cost of computing time, and the availability of well-tested forcefields make molecular simulation increasingly attractive for chemical engineers. We present here several applications...
  8. SB Donald, JK Navin, I Harrison
    Journal of Chemical Physics 139, 214707 (2013)
    A dynamically biased (d-) precursor mediated microcanonical trapping (PMMT) model of the ac- tivated dissociative chemisorption of methane on Pt(111) is applied to a wide range of dissociative sticking experiments, and, by detailed balance, to the methane product state distributions from the...

2012

  1. V Eyert, A Mavromaras, D Rigby, W Wolf, M Christensen, M Halls, C Freeman, P Saxe, and E Wimmer
    N. Iwamoto et al. (eds.), Molecular Modeling and Multiscaling Issues for Electronic Material Applications, Springer 2012
    The prediction of materials properties using atomic-scale simulations offers exciting and unprecedented opportunities to expand the capabilities of electronic devices, to create novel systems, and to improve their reliability. This contribution discusses the current state of atomic-scale...
  2. A Gannouni, Xavier Rozanska, B Albela, M Saïd Zina, F Delbecq, L Bonneviot, and A Ghorbel
    Journal of Catalysis 289, no. C (May 1, 2012): 227–237
    The site occupancy of the various oxidation state of palladium supported on mesostructured porous aluminosilica of Al-MCM-41 type was studied combining density functional theory (DFT), FTIR, and Raman investigations. The study focuses on the usual +2 oxidation state highly dispersed during...
  3. T Tranh, Xavier Rozanska, F Delbecq, and P Sautet
    Physical Chemistry Chemical Physics 14, no. 10 (2012): 3369.
    The initial step for silicate and aluminosilicate condensation is studied in water in the presence of a realistic tetrapropylammonium template under basic conditions. The model corresponds to the synthesis conditions of ZSM5. The free energy profile for the dimer formation ((OH)₃Si–O–Si–(OH)₂O⁻ or...
  4. R Kerber, A Kermagoret, E Callens, P Florian, D Massiot, A Lesage, C Copéret, F Delbecq, Xavier Rozanska, and P Sautet
    Journal of the American Chemical Society 134, no. 15 (April 18, 2012): 6767–6775.
    The determination of the nature and structure of surface sites after chemical modification of large surface area oxides such as silica is a key point for many applications and challenging from a spectroscopic point of view. This has been, for instance, a long-standing problem for silica reacted...
  5. Shi, S, P Lu, Z Liu, Y Qi, LG Hector Jr., H Li, and SJ Harris
    Journal of the American Chemical Society 134, no. 37: 15476–15487.
    The mechanism of Li⁺ transport through the solid electrolyte interphase (SEI), a passivating film on electrode surfaces, has never been clearly elucidated despite its overwhelming importance to Li-ion battery operation and lifetime. The present paper develops a multiscale theoretical methodology to...
  6. J Wróbel, L G Hector Jr., Walter Wolf, S L Shang, Z-K Liu, and K J Kurzydłowski
    Journal of Alloys and Compounds, 512(1), 296–310 (2012)
    Thermodynamic and mechanical properties of the six known phases in the La–Mg phase diagram, viz. LaMg, LaMg₂, LaMg₃, La₅Mg₄₁, La₂Mg₁₇, and LaMg₁₂, and their elemental antecedents, Mg and La, are computed with density functional theory (DFT) using the PBE and PBEsol exchange-correlation functionals...
  7. Kerscher, T. C., Schöllhammer, G., Herzig, P., Walter Wolf, Podloucky, R., & Müller, S. (n.d.). First-principles study of hydrogen ordering in lanthanum hydride and its effect on the metal-insulator transition. Prb.Aps.org.
    Physical Review B. 86 (1) 014107 (2012)
    We discuss the structural details and the ordering of hydrogen in LaHx for 2⩽x⩽3. To this end, we combine first-principles calculations with the cluster-expansion method. This approach allows us to follow the H occupation of the interstitial sites within the face-centered cubic matrix of La atoms....
  8. Amra Peles
    Journal of Materials Science, 47(21), 7542–7548 (2012)
    We implement DFT calculations by a Hubbard-like correction for localized strongly correlated electrons, coupled with a generalized gradient approximation to the exchange-correlation functional to elucidate the role of the ceria based catalytically active supports for the chemical reactions...

2011

  1. S L Shang, L G Hector Jr., Y Wang, and Z K Liu
    Phys. Rev. B 83, 224104 (2011)
    An anomalous energy pathway with energetically equivalent double saddle points for vacancy mediated self-diffusion within an hcp-Ti basal plane is unveiled by density functional theory. Examination of migration pathway and phonon force constants suggests that the migrating atom tries to follow the...
  2. V. Eyert
    Phys. Rev. Lett. 107, 016401 (2011)
    New calculations for vanadium dioxide, one of the most controversially discussed materials for decades, reveal that band theory as based on density functional theory is well capable of correctly describing the electronic and magnetic properties of the metallic as well as both the insulating M1 and...
  3. M Harb, P Sautet, Pascal Raybaud
    The Journal of Physical Chemistry C 115, no. 39 (October 6, 2011): 19394–19404.
    Extension of the absorption properties of TiO₂ photocatalytic materials to the visible part of the solar spectrum is of major importance for energy and cleaning up applications. We carry out a systematic study of the N-doped anatase TiO₂ material using spin-polarized density functional theory (DFT...
  4. Chotard, Jean-Noël, Wan Si Tang, Pascal Raybaud, and Raphaël Janot
    Chemistry - A European Journal 17, no. 44 (September 27, 2011): 12302–12309.
    KSi silicide can absorb hydrogen to directly form the ternary KSiH₃ hydride. The full structure of α-KSiD₃, which has been solved by using neutron powder diffraction (NPD), shows an unusually short Si-D lengths of 1.47 Å. Through a combination of density functional theory (DFT) calculations and...
  5. L Schimka, J Harl, and G Kresse
    J. Chem. Phys. 134, 024116 (2011)
    We introduce the hybrid functional HSEsol. It is based on PBEsol, a revised Perdew–Burke–Ernzerhof functional, designed to yield accurate equilibrium properties for solids and their surfaces. We present lattice constants, bulk moduli, atomization energies, heats of formation, and band gaps for...
  6. R Mahesh Kumar and V Subramanian
    International Journal of Hydrogen Energy, vol 36(17), pp 10737-10747
    The interaction energies (IEs) of H₂ and various organic ligands have been computed using coupled-cluster method with singles, doubles, and noniterative triples (CCSD(T)) at the complete basis set (CBS) limit. The density fitting-density functional theory-symmetry adapted perturbation theory (DF-...
  7. H Wang, Volker Eyert, Udo Schwingenschlögl
    J. Phys. Condens. Matter 23 (2011) 116003
    We present results from an electronic structure investigation of the chromium halides CrCl₃, CrBr₃, and CrI₃, as obtained by the linearized augmented plane wave method of density functional theory. Our interest focuses on the chloride. While all three halides display strong ferromagnetic coupling...
  8. R Weihrich, S F Matar, I Anusca, F Pielnhofer, P Peter, F Bachhuber, and Volker Eyert
    Journal of Solid State Chemistry 184, no. 4 (April 1, 2011): 797–804
    The crystallographic and electronic structures of compounds related to parkerite (Bi₂Ni₃S₂) are investigated with respect to the recently reported occurrence (Bi₂Pd₃Se₂) and absence (Bi₂Pd₃S₂) of superconductivity. Similarities and differences of the crystal structures are discussed within the...
  9. Xavier Rozanska, P Sautet, F Delbecq, F Lefebvre, S Borshch, H Chermette, J Basset, and E Grinenval
    Physical Chemistry Chemical Physics 13, no. 35 (2011): 15955.
    doi:
    The process of grafting H₃PMo₁₂O₄₀ onto silica surfaces is studied using periodic density functional theory methods. For surfaces with a high hydroxyl coverage, the hydroxyl groups are consumed by the polyoxometalate protons, resulting in water formation and the creation of a covalent bond between...
  10. S Bratos, M Wulff, J-C Leicknam, R Vuilleumier, and Xavier Rozanska
    Ukr. J. Phys. 2011. Vol. 56, No. 8 56 (2011): 763.
    doi:
    The recombination of laser-dissociated iodine molecules dissolved in CCl₄ is explored by time-resolved x-ray diffraction. The x-ray pulses employed in our experiments were generated by the ESRF synchrotron in Grenoble. The solvent contribution to the mea- sured signals was eliminated using...
  11. F Biscay, C Chizallet, B Creton, A Fecant, N, P, C Nieto-Draghi, P Raybaud, B Rousseau, P Ungerer
    L'actualité chimique 353-354: 66 (2011)
    doi:
    La modélisation moléculaire permet aujourd'hui de simuler les matériaux ou les fluides à l'échelle du nanomètre, voire de l'ångström, en s'appuyant sur les lois les plus fondamentales de la mécanique quantique ou de la mécanique statistique. Cette discipline de la chimie...
  12. E El Ahmara, B Creton, A Valtz, C Coquelet, V Lachet, D Richon, P Ungerer
    Fluid Phase Equilibria 304, 21 (2011)
    In the present work, we report isothermal vapour–liquid equilibrium data for two binarysystems: nitrogen–sulphur dioxide and oxygen–sulphur dioxide at four temperatures (323.15, 343.15, 373.15, and 413.15 K) and pressures up to 85 MPa. These data were simultaneously obtained from experimental...
  13. Schöllhammer, G., Herzig, P., Walter Wolf, Vajda, P., & Yvon, K.
    Physical Review B, 84(9), 094122
    Results from first-principles investigations of the energetical, structural, electronic, and vibrational properties of model structures probing the metal-rich region of the lanthanum-hydrogen system, i.e., the region of the solid solution of hydrogen in lanthanum, are presented. We have studied the...
  14. Wróbel, J., Hector, L. G., Jr, Walter Wolf, & Kurzydłowski, K. J.
    Materials Science Forum, 690, 15–18 (2011)
    Lattice parameters, electronic and vibrational energies, enthalpies of formation at 0 and 298 K, the elasticity tensor components, Cij, polycrystalline bulk, shear and Young’s moduli based on the Hill criteria were computed for LaMg, LaMg₂, LaMg₃, La₅Mg₄₁, La₂Mg₁₇, and LaMg₁₂. The quasiharmonic...
  15. S M Opalka, O M Løvvik, S C Emerson, Y She, T H Vanderspurt
    Journal of Membrane Science 375, 96–103 (2011)
    Atomic modeling was conducted to investigate the origin of S interactions with Pd alloy H selective membrane candidates selected from the Pd–Cu, Pd–Ag, and Pd–Au binary systems, as well as their constitutive metals. The electronic characteristics of these alloy/metal systems played a more...
  16. S Ganeshan, L G Hector Jr., and Z K Liu
    Acta Materialia 59, 3214–3228 (2011)
    Diffusion in dilute Mg–X alloys, where X denotes Al, Zn, Sn and Ca impurities, was investigated with first-principles density functional theory in the local density approximation. Impurity diffusion coefficients were computed as a function of temperature using the 8-frequency model which provided...
  17. Shao, M., Peles, A., Shoemaker, K., Gummalla, M., Njoki, P. N., Luo, J., & Zhong, C.-J
    The Journal of Physical Chemistry Letters, 2(2), 67–72 (2011)
    The increase in oxygen binding energy was previously proposed to account for the lower oxygen reduction activity of a Pt monolayer supported on Au(111) single crystal than that on Pd(111) and pure Pt(111) surfaces. This single-crystal based understanding, however, cannot explain the new finding of...
  18. Shao, M., Peles, A., & Shoemaker, K
    Nano Letters, 11(9), 3714–3719 (2011)
    We determined the size-dependent specific and mass activities of the oxygen reduction in HClO4 solutions on the Pt particles in the range of 1–5 nm. The maximal mass activity at 2.2 nm is well explained based on density functional theory calculations performed on fully relaxed nanoparticles. The...
  19. De Moor, B. A., Ghysels, A., Reyniers, M.-F., Van Speybroeck, V., Waroquier, M., & Marin, G. B
    Journal of Chemical Theory and Computation, 7(4), 1090–1101 (2011)
    An efficient procedure for normal-mode analysis of extended systems, such as zeolites, is developed and illustrated for the physisorption and chemisorption of n-octane and isobutene in H-ZSM-22 and H-FAU using periodic DFT calculations employing the Vienna Ab Initio Simulation Package....
  20. D A Bardwell, C S Adjiman, Y A Arnautova, E Bartashevich, S X M Boerrigter, D E Braun, A J Cruz-Cabeza, G M Day, R G Della Valle, G R Desiraju, B P van Eijck, J C Facelli, M B Ferraro, D Grillo, M Habgood, D W M Hofmann, F Hofmann, K V J Jose, P G Karamertzanis, A V Kazantsev, J Kendrick, L N Kuleshova, F J J Leusen, A V Maleev, A J Misquitta, S Mohamed, R J Needs, M A Neumann, D Nikylov, A M Orendt, R Pal, C C Pantelides, C J Pickard, L S Price, S L Price, H A Scheraga, J van de Streek, T S Thakur, S Tiwari, E Venuti, and I K Zhitkov
    Acta Cryst (2011). B67, 535-551
    Following on from the success of the previous crystal structure prediction blind tests (CSP1999, CSP2001, CSP2004 and CSP2007), a fifth such collaborative project (CSP2010) was organized at the Cambridge Crystallographic Data Centre. A range of methodologies was used by the participating groups in...
  21. P E Krajewski, L G Hector, Y Qi, R K Mishra, A K Sachdev, A F Bower, and W A Curtin
    Journal of Materials 63, no. 11: 24–32. (2011)
    A multi-scale, computational design approach for aluminum sheet alloys, which includes key inputs from the electronic, atomistic, microstructural, and continuum length scales, is re- viewed within the context of room and elevated temperature forming. Specific examples, which are aimed at improv-...

2010

  1. C Hinkle, R Galatage, R Chapman, E Vogel, H Alshareef, Clive Freeman, Erich Wimmer, H Niimi, A Li-Fatou, J Shaw, and J Chambers
    Applied Physics Letters 96(10), 3502 (2010)
    Effective work function (EWF) changes of TiN/HfO₂ annealed at low temperatures in different ambient environments are correlated with the atomic concentration of oxygen in the TiN near the metal/dielectric interface. EWF increases of 550 meV are achieved with anneals that incorporate oxygen...
  2. HR Chauke, B Minisini, R Drautz, D Nguyen-Manh, PE Ngoepe, and DG Pettifor
    Intermetallics 18(4), 417 (2010)
    The deleterious low-temperature tetragonal phases in prototypical Pt-based superalloys have variously been reported as taking the tI16-U₃Si (DOc), tI16-Ir₃Si (DOc′) and tP16-Pt₃Ga structure-types in contrast to the high-temperature cubic cP4-Cu₃Au (L12) phase. We have investigated the relative...
  3. C Chizallet and P Raybaud
    Chem. Phys. Chem. 11, 105 (2010)
    Local structure resolved: The debated nature of Brønsted acid sites on amorphous silica-alumina is investigated by DFT calculations. Bridging Si-(OH)-Al and pseudo-bridging silanols, in through-space interaction with Al<sub>IV</sub> or Si<sub>IV</sub>, are deprotonated by...
  4. Y Qi, H Guo, LG Hector, Jr., and A Timmons
    J. Electrochem. Soc. 157(5), A558 (2010)
    Density functional theory (DFT) is used to reveal that the polycrystalline Young’s modulus ͑ E of graphite triples as it is lithiated to LiC<sub>6</sub>. This behavior is captured in a linear relationship between E and lithium concentration suitable for continuum-scale models aimed at...
  5. Erich Wimmer, R Najafabadi, G A Young Jr., J D Ballard, T M Angeliu, J Vollmer, J J Chambers, H Niimi, J B Shaw, Clive Freeman, Mikael Christensen, Walter Wolf, and Paul Saxe
    Journal of Physics: Condensed Matter vol. 22 (38) pp. 384215 (2010)
    Computational materials science based on ab initio calculations has become an important partner to experiment. This is demonstrated here for the effect of impurities and alloying elements on the strength of a Zr twist grain boundary, the dissociative adsorption and diffusion of iodine on a...
  6. S Ganeshan, LG Hector Jr, ZK Liu
    Computational Materials Science 50, no. 2: 301–307. (2010)
    Self-diffusion coefficients for hcp Mg and Zn have been calculated from first-principles as a function of temperature, within the generalized gradient and local density approximations. The climbing image nudged elastic band (CI-NEB) method has been used to provide minimum energy pathways and...
  7. J Kwon, M Dai, Mathew D Halls, YJ Chabal
    Applied Physics Letters 97, 162903 (2010)
    We demonstrate that interfacial SiO₂, usually formed during high-k oxide growth on silicon using ozone (O₃), is suppressed during Al₂O₃ atomic layer deposition (ALD) by decreasing the O₃ flow rate. First-principles calculations indicate that oxygen introduced by the first low-dose O₃ exposure is...
  8. W Cheng, L Liu, P Yu, Z Ma, and S Mao
    Ann. Phys. (2010) vol. 1 pp. 8
    In this paper we have applied first-principle density-functional theory to calculate some of the interesting roles played by vacancies in material properties, such as magnetic properties and complex formation. We use as examples our recent results on vacancies in group III-V semiconductors like GaN...
  9. L. Schimka, J. Harl, A. Stroppa, A. Grüneis, M. Marsman, F. Mittendorfer, and G. Kresse
    Nature Mater. 9, 741–744 (2010)
    Kohn–Sham density functional theory is the workhorse computational method in materials and surface science. Unfortunately, most semilocal density functionals predict surfaces to be more stable than they are experimentally. Naively, we would expect that consequently adsorption energies on surfaces...
  10. T Nogareta, W A Curtin, J A Yasi, L G Hector Jr, and D R Trinkle
    Acta Mater. 58, 4332 (2010)
    The gamma surfaces in the pyramidal I {1 −1 0 1} and II {1 1−2 2} planes for hexagonal close packed Mg have been calculated using two embedded-atom-method potentials and by ab initio methods, and reasonable agreement is obtained for key stacking fault energies. Screw and edge 〈c + a〉 dislocation...
  11. Jürgen Hafner
    J. Phys.: Condens. Matter 22 384205 (2010)
    During the last 20 years computer simulations based on a quantum-mechanical description of the interactions between electrons and atomic nuclei have developed an increasingly important impact on materials science, not only in promoting a deeper understanding of the fundamental physical phenomena,...
  12. J Harl, L Schimka, and G Kresse
    Phys. Rev. B 81, 115126 (2010)
    We present lattice constants, bulk moduli, and atomization energies of solids using the correlation energy evaluated within the adiabatic connection fluctuation-dissipation framework and applying the random-phase approximation. Recently, we have shown [_Phys. Rev. Lett._ 103 056401 (2009)] that...
  13. J Herbst, L G Hector, & Walter Wolf
    Physical Review B, 82(2), 024110
    Systematic properties of the AGaH₄ alkali gallium hydrides (A=Li, Na, K, Rb, and Cs) are investigated within density functional theory. Seven ground-state crystal structures are identified, with two energetically indistinguishable structures found for both LiGaH₄, whose structure is as yet...
  14. G P M Leyson, W A Curtin, L. G. Hector Jr, and C. F. Woodward
    Nature Materials 9, 750 (2010)
    Despite significant advances in computational materials science, a quantitative, parameter-free prediction of the mechanical properties of alloys has been difficult to achieve from first principles. Here, we present a new analytic theory that, with input from first-principles calculations, is able...
  15. M Christensen, TM Angeliu, JD Ballard, J Vollmer, R Najafabadi, and E Wimmer
    Journal of Nuclear Materials 404, no. 2: 121–127. (2010)
    Effects of twenty impurity and alloy elements on the strength of a Zr(0001)/Zr(0001) Σ7 twist grain boundary were studied using a first-principles density functional approach. A ranking in the order of most weakening to most strengthening was: Cs, I, He, Te, Sb, Li, O, Sn, Cd, H, Si, C...

2009

  1. Mikael Christensen, Jake D Ballard, Thomas M Angeliu, James Vollmer, Reza Najafabadi, Erich Wimmer
    Proceedings of Top Fuel 2009, paper 2165
    doi:
    Effects of twenty impurity and alloy elements on the strength of a Zr(0001)/Zr(0001) Σ7 twist grain boundary were studied using a first-principles density functional approach. A ranking in the order of most weakening to most strengthening was: Cs, I, He, Te, Sb, Li, O, Sn, Cd, H, Si, C, N, B, U, Ni...
  2. E Krebs, A Daudin, and P. Raybaud
    Oil & Gas Sci. Tech. Rev. IFP 64, 707 (2009)
    This paper reports an overview of recent DFT studies on the atomic scale characterization of Co(Ni)MoS active phases used in selective hydrodesulfurization (HDS) catalysis. A peculiar attention is paid to the effect of the sulfo-reductive reaction conditions on the stability and nature of the...
  3. S L Shang, L G Hector Jr, Y Wang, H Zhang, and Z K Liu
    J. Phys.: Condens. Matter
    Elasticity tensor components, Cij, the crystallographic dependence of Poisson’s ratio, the phase stability, and vibrational spectra are computed for nonmagnetic and magnetic CeMg (1:1 Ce:Mg) structures using density functional theory. Results from both the generalized gradient approximation (GGA),...
  4. J. Harl and G. Kresse
    Phys. Rev. Lett. 103, 056401 (2009)
    The adiabatic-connection fluctuation-dissipation theorem suggests that the correlation energy in the random phase approximation is a suitable complement to exact exchange. We show that lattice constants, bulk moduli, and atomization energies of solids evaluated using this approximation are in very...
  5. X Luo, W Zhou, S V Ushakov, A Navrotsky, and A A Demkov
    Phys. Rev. B 80, 134119 (2009)
    We use a combination of density functional theory and calorimetric measurements to investigate the monoclinic to tetragonal transition in hafnia and zirconia. We measure the transition enthalpies to be 8.4±0.7 kJ/mol in hafnia and, as previously reported, 5.272±0.544 kJ/mol in zirconia. Calculated...
  6. Tkatchenko, A., & Scheffler, M. (2009).
    Physical Review Letters, 102(7), 073005 (2009)
    We present a parameter-free method for an accurate determination of long-range van der Waals interactions from mean-field electronic structure calculations. Our method relies on the summation of interatomic C6 coefficients, derived from the electron density of a molecule or solid and accurate...

2008

  1. Erich Wimmer
    Journal of Physics: Condensed Matter 20, 064243 (2008)
    A workshop, ‘Theory Meets Industry’, was held on 12–14 June 2007 in Vienna, Austria, attended by a well balanced number of academic and industrial scientists from America, Europe, and Japan. The focus was on advances in ab initio solid state calculations and their practical use in industry. The...
  2. Erich Wimmer, Walter Wolf, Jürgen Sticht, Paul Saxe, Reza Najafabadi, George A Young
    Physical Review B Condensed Matter 77, 134305 (2008)
    The temperature-dependent diffusion coefficients of interstitial hydrogen, deuterium, and tritium in nickel are computed using transition state theory. The coefficient of thermal expansion, the enthalpy and entropy of activation, and the pre-exponential factor of the diffusion coefficient are obtained...
  3. Joachim Paier, Martijn Marsman, Georg Kresse
    Physical Review B Condensed Matter 78, 121201 (2008)
    We have calculated static and dynamic response properties for several semiconducting and insulating solids using hybrid functionals, which admix a small fraction of nonlocal Fock exchange to an otherwise semilocal density functional. The calculated static and dynamic properties are clearly improved...
  4. Jürgen Hafner
    Journal of Computational Chemistry 29(13), 2044-2078 (2008)
    During the past decade, computer simulations based on a quantum-mechanical description of the interactions between electrons and between electrons and atomic nuclei have developed an increasingly important impact on solid-state physics and chemistry and on materials science—promoting not only a...
  5. Louis Hector Jr, J. F Herbst
    Journal of Physics: Condensed Matter 20(6), 064229 (2008)
    Solid state systems for hydrogen storage continue to be the focus of considerable international research, driven to a large extent by technological demands, especially for mobile applications. Density functional theory (DFT) has become a valuable tool in this effort. It has greatly expanded our...
  6. M Rotter, Peter Franz Rogl, A Grytsiv, Walter Wolf, M Krisch
    Physical Review B Condensed Matter 77, 144301 (2008)
    Skutterudite based materials are important for thermoelectric applications. In order to be able to tune the thermoelectric properties, it is necessary to understand the mechanism of thermal conductivity, which, in turn, is strongly influenced by the lattice dynamics. The lattice dynamics of the...
  7. Martijn Marsman, Joachim Paier, Alessandro Stroppa, Georg Kresse
    Journal of Physics: Condensed Matter 20, 064201 (2008)
    We present an overview of the description of structural, thermochemical, and electronic properties of extended systems using several well known hybrid Hartree–Fock/density-functional-theory functionals (PBE0, HSE03, and B3LYP). In addition we address a few aspects of the evaluation of the Hartree–...
  8. Roman Wahl, Doris Vogtenhuber, Georg Kresse
    Physical Review B Condensed Matter 78(10), 104116 (2008)
    The structural, electronic, and phonon properties of the cubic and tetragonal phase of SrTiO₃ and BaTiO₃ are studied from ab initio. The calculations are performed in the projector augmented wave density-functional theory framework using the local density approximation, gradient corrected...
  9. Christopher Woodward, D. R Trinkle, Louis Hector Jr, D. L Olmsted
    Physical Review Letters 100(4), 5507 (2008)
    The strain field of isolated screw and edge dislocation cores in aluminum are calculated using densityfunctional theory and a flexible boundary condition method. Nye tensor density contours and differential displacement fields are used to accurately bound Shockley partial separation distances. Our...
  10. René Windiks, Erich Wimmer, L Pourovskii, S Biermann, Antoine Georges
    Journal of Alloys and Compounds 459(1-2), 438-446 (2008)
    Structural and electronic properties of the α- and γ-phases of cerium sesquisulfide, Ce₂S₃, are examined by first-principles calculations using the GGA+U extension of density functional theory. The strongly correlated f-electrons of Ce are described by a Hubbard-type on-site Coulomb repulsion...
  11. Y Zhao and D G Truhlar
    Acc. Chem. Res. 41, 157 (2008)
    Although density functional theory is widely used in the computational chemistry community, the most popular density functional, B3LYP, has some serious shortcomings: (i) it is better for main-group chemistry than for transition metals; (ii) it systematically underestimates reaction barrier heights...
  12. J Harl and G Kresse
    Phys. Rev. B 77, 045136 (2008)
    We present first-principles calculations for the fcc noble gas solids Ne, Ar, and Kr applying the adiabatic connection fluctuation-dissipation theorem (ACFDT) to evaluate the correlation energy. The ACFDT allows us to describe long-range correlation effects including London dispersion or van der...
  13. A Stroppa and G Kresse
    New J. Phys. 10 063020 (2008)
    A study of the adsorption of CO on late 4d and 5d transition metal (111) surfaces (Ru, Rh, Pd, Ag, Os, Ir and Pt) considering atop and hollow site adsorption is presented. The applied functionals include the gradient-corrected Perdew–Burke–Ernzerhof (PBE) and Becke–Lee–Yang–Parr (BLYP) functionals...
  14. F Oba, A Togo, I Tanaka, J Paier, and G Kresse
    Phys. Rev. B 77, 245202 (2008)
    First-principles calculations based on hybrid Hartree-Fock density functionals provide a clear picture of the defect energetics and electronic structure in ZnO. Among the donorlike defects, the oxygen vacancy and hydrogen impurity, which are deep and shallow donors, respectively, are likely to form...
  15. Francis, M. F., Neurock, M. N., Zhou, X. W., Quan, J. J., Wadley, H. N. G., & Webb, E. B
    Journal of Applied Physics, 104(3), 034310.
    Molecular dynamics simulations and selected experiments have been carried out to study the growth of Cu films on (010) bcc Ta and the deposition of CuxTa1−x alloy films on (111) fcc Cu. They indicate that fcc Cu films with a (111) texture are always formed when Cu is deposited on Ta surfaces. These...
  16. J Wróbel and J Piechota
    Solid State Communications 146 324 (2008)
    Elastic properties of ZnO polymorphs: B4 (wurtzite), B3 (zinc-blende), B1 (rocksalt) phases, and yet experimentally undiscovered B2 (CsCl) phase were computed using the first-principles plane-wave pseudo-potential method in the scheme of density functional theory. The results obtained for the most...

2007

  1. A Tejeda, Erich Wimmer, P Soukiassian, D Dunham, E Rotenberg, J. D Denlinger, E. G Michel
    Physical Review B Condensed Matter 75, 195315 (2007)
    The structure of the Si-terminated 3C-SiC(001)-c(4×2) surface reconstruction is determined using synchrotron-radiation-based x-ray photoelectron diffraction from the Si 2p and C 1s core levels. Only the alternating up-and-down dimer (AUDD) model reproduces satisfactorily the experimental results....
  2. Alessandro Stroppa, Konstantinos Termentzidis, Joachim Paier, Georg Kresse, Jürgen Hafner
    Physical Review B Condensed Matter 76, 195440 (2007)
    We present a detailed study of the adsorption of CO on Cu, Rh, and Pt (111) surfaces in top and hollow sites. The study has been performed using the local density approximation, the gradient corrected functional PBE, and the hybrid Hartree-Fock density functionals PBE0 and HSE03 within the...
  3. Cesare Franchini, Raimund Podloucky, Joachim Paier, Martijn Marsman, Georg Kresse
    Physical Review B Condensed Matter 75, 195128 (2007)
    We present density functional theory (DFT) calculations for MnO, Mn₃O₄, α-Mn₂O₃, and β-MnO₂, using different gradient corrected functionals, such as Perdew-Burke-Ernzerhof (PBE), PBE+U, and the two hybrid density functional Hartree-Fock methods PBE0 and Heyd-Scuseria-Ernzerhof (HSE). We investigate...
  4. E Bauer, A Grytsiv, Xing-Qiu Chen, N Melnychenko-Koblyuk, G Hilscher, H Kaldarar, H Michor, E Royanian, G Giester, M Rotter, Raimund Podloucky, P Rogl
    Physical Review Letters 99, 217001 (2007)
    Combining experiments and ab initio models we report on SrPt₄Ge₁₂ and BaPt₄Ge₁₂ as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge atoms. Below Tc=5.35 and 5.10 K forBaPt₄Ge₁₂ and SrPt₄Ge₁₂, respectively, electron-phonon...
  5. Louis Hector Jr, J. F Herbst, Walter Wolf, Paul Saxe, Georg Kresse
    Physical Review B Condensed Matter 76, 014121 (2007)
    A systematic investigation of the alkaline earth hydrides BeH₂, MgH₂, CaH₂, SrH₂, BaH₂, the corresponding deuterides, and their antecedent metals is reported. We calculate lattice parameters, electronic and vibrational energies, enthalpies of formation at 0 and 298 K, components of the elasticity...
  6. M Shishkin, Martijn Marsman, Georg Kresse
    Physical Review Letters 99, 246403 (2007)
    Self-consistent GW calculations, maintaining only the quasiparticle part of the Green's function G, are reported for a wide class of materials, including small gap semiconductors and large gap insulators. We show that the inclusion of the attractive electron-hole interaction via an effective...
  7. Pascal Raybaud
    Applied Catalysis A: General 322, 76-91 (2007)
    This paper is a review of recent advances accomplished in the field of hydrotreatment (HDT) sulfide catalysts and using theoretical approaches based on the density functional theory (DFT) combined with thermodynamic models and microkinetic models. We illustrate first numerous concepts of modern DFT...
  8. Susanne M Opalka, O M Løvvik, Hendrik W Brinks, Paul Saxe, Bjørn C Hauback
    Inorganic Chemistry 46(4), 1401-1409 (2007)
    First-principles modeling, experimental, and thermodynamic methodologies were integrated to facilitate a fundamentally guided investigation of quaternary complex hydride compounds within the bialkali Na−Li−Al−H hydrogen storage system. The integrated approach has broad utility for the discovery,...
  9. X Chen, Walter Wolf, Raimund Podloucky, Peter Franz Rogl
    Physical Review B Condensed Matter 76, 092102 (2007)
    By means of a density functional theory approach, we calculated the structural stabilities, electronic structure, elastic constants, and vibrational properties of the compound TiPd₂. The results indicate that the tetragonal MoSi₂-type (C11b) structure is unstable, whereas the orthorhombically...
  10. XQ Chen, Walter Wolf, Raimund Podloucky, Peter Franz Rogl
    Physical Review B Condensed Matter 76, 014424 (2007)
    By an ab initio density functional approach, structural, magnetic, vibrational, and thermodynamic properties of HfMn₂ were studied. These properties were derived for the C14, C15, and C36 crystal structures, revealing a close energetical competition between the ferromagnetically ordered phases and...
  11. Z Stoeva, B Jäger, R Gomez, S Messaoudi, M Ben Yahia, X Rocquefelte, G B Hix, W Wolf, J J Titman, R Gautier, P Herzig, D H Gregory
    J. Am. Chem. Soc. 129, 1912 (2007)
    The layered ternary nitride LiNiN shows an interesting combination of fast Li+ ion diffusion and metallic behavior, properties which suggest potential applications as an electrode material in lithium ion batteries. A detailed investigation of the structure and properties of LiNiN using powder...
  12. Xing-Qiu Chen, Walter Wolf, Raimund Podloucky, Peter Franz Rogl, Martijn Marsman
    Europhysics Letters (EPL) 67(5), 807-813 (2007)
    Based on density-functional calculations, we propose that ZrMn₂ is a polymorphic material. We predict that at low temperatures the cubic C15, and the hexagonal C14 and C36 structures of the Laves phase compound ZrMn₂ are nearly equally stable within 0.3 kJ mol⁻¹ or 30 K. This degeneracy occurs when...
  13. F Faure, B Rousseau, V Lachet, Philippe Ungerer
    Fluid Phase Equilibria (2007) vol. 261 (1-2) pp. 168-175
    We present molecular simulation results of solubility and self-diffusion of carbon dioxide and hydrogen sulfide in linear polyethylene melts. Simulations were carried out at 433 K and pressures in the range 0.1–10 MPa. Solubilities were computed using Monte Carlo simulations in the osmotic ensemble...
  14. J Paier, M Marsman, and G Kresse
    J. Chem. Phys. 127, 024103 (2007)
    The B3LYP hybrid functional has shown to successfully predict a wide range of molecular properties. For periodic systems, however, the failure to attain the exact homogeneous electron gas limit as well as the semiempirical construction turns out to be a major drawback of the functional. We...
  15. J F Herbst and L G Hector Jr.
    Journal of Alloys and Compounds 446–447, 188–194 (2007)
    Systematic theoretical results for La(TM)₅Hₙ materials with TM one of the magnetic transition metals Fe, Co, or Ni are discussed. For TM = Co, Ni the antecedent LaCo₅ and LaNi₅ intermetallics and hydrides are well known. While no La–Fe compounds exist, LaFe₅ hydrides are predicted to form by both...

2006

  1. Joachim Paier, Martijn Marsman, Kerstin Hummer, Georg Kresse, I. C Gerber, Janos G Ángyán
    Journal of Chemical Physics 124(15), 4709 (2006)
    Hybrid Fock exchange/density functional theory functionals have shown to be very successful in describing a wide range of molecular properties. For periodic systems, however, the long-range nature of the Fock exchange interaction and the resultant large computational requirements present a major...
  2. Marek Gajdoš, Kerstin Hummer, Georg Kresse
    Physical Review B Condensed Matter 73, 045112 (2006)
    In this work we derive closed expressions for the head of the frequency-dependent microscopic polarizability matrix in the projector-augmented wave (PAW) methodology. Contrary to previous applications, the lon- gitudinal expression is utilized, resulting in dielectric properties that are largely...
  3. Pascal Raybaud, Hervé Toulhoat
    Oil & Gas Science and Technology-Revue de l'IFP 61(4), 580 (2006)
    doi:
    In what follows, it is reported the detailed account of the presentations and discussions taking place at the round table on Molecular Modeling and High-Throughput Experimentation (HTE), meeting the challenges of catalysts, chemicals and materials design. After the short introduction by H. Toulhoat...
  4. Louis Hector Jr, Pablo D Zavatteri, Allan F Boewer
    GM Research & Development Center, 63 (2006)
    doi:
    The present work extends previous work on modeling the effect of a sinusoidal interface pattern on interfacial toughening between identical materials by incorporating both elastic-perfectly plastic and elastic-power-law-hardening models. The materials are assumed to be bonded by an infinitesimally-...
  5. J Paier, M Marsman, K Hummer, G Kresse, I C Gerber, J G Ángyán
    J. Chem. Phys. 125, 249901 (2006)
  6. Grimme, S
    Journal of Computational Chemistry, 27(15), 1787–1799. (2006)
    A new density functional (DF) of the generalized gradient approximation (GGA) type for general chemistry applications termed B97-D is proposed. It is based on Becke's power-series ansatz from 1997 and is explicitly parameterized by including damped atom-pairwise dispersion corrections of the...
  7. T Jaroń, W Grochala, and R Hoffmann
    J. Mater. Chem.16, 1154 (2006)
    We theoretically examine four hypothetical ternary lanthanide hydrides, CsLn<sup>II</sup>H<sub>3</sub> and Cs<sub>2</sub>Ln<sup>II</sup>H<sub>4</sub>, where Ln<sup>II</sup> = Yb, Tm. We optimize their crystal unit cells in the...

2005

  1. Clint B Geller, Richard W Smith, John E Hack, Paul Saxe, Erich Wimmer
    Scripta Materialia 52(3), 205-210 (2005)
    The Rice–Thomson parameter has been evaluated as a computational screening tool for identifying ductilizing additives to Mo. Our results support a hypothesis that soluble additives that are hcp in their pure form weaken the Mo bcc lattice against shears in the (110) plane that are associated with...
  2. Joachim Paier, Robin Hirschl, Martijn Marsman, Georg Kresse
    Journal of Chemical Physics 122, 234102 (2005)
    Present local and semilocal functionals show significant errors, for instance, in the energetics of small molecules and in the description of band gaps. One possible solution to these problems is the introduction of exact exchange and hybrid functionals. A plane-wave-based algorithm was implemented...
  3. C Colinet, Walter Wolf, Raimund Podloucky, A Pasturel
    Applied Physics Letters 87(4), 1910 (2005)
    In order to clarify the allotropic structural properties of TiSi₂ we calculated by means of an ab initio density functional approach the total energies of the C49, C54, and C40 crystal structures of the bulk compound. We found that at T=0 K the C49 structure of TiSi₂ is its most stable phase...
  4. J. F Herbst, Louis Hector Jr
    Physical Review B Condensed Matter 72, 125120 (2005)
    A density functional theory investigation of the recently identified hydrogen storage reaction LiNH₂ + LiH ↔ Li₂NH + H₂ is described. The electronic structure and enthalpy of formation ΔH of each constituent are calculated in both the generalized gradient approximation (GGA) and the local density...
  5. M Sternik, K Parlinski
    Journal of Chemical Physics 122, 064707 (2005)
    First principles calculations of the phonon dispersion relations and the phonon density of states for three zero-pressure zirconia phases are presented. The phonon dispersion relations of the tetragonal and monoclinic phases do not exhibit the imaginary frequencies, contrary to the cubic phase for...
  6. Walter Wolf, Jürgen Sticht, Alexander Mavromaras, B Leblanc, Paul Saxe, Erich Wimmer
    Materials Science-Poland 23(2), 365 (2005)
    doi:
    The simulation of vibrational properties and finite temperature effects based on ab initio calculation of phonons within the direct approach is discussed.
  7. XQ Chen, Walter Wolf, Raimund Podloucky, Peter Franz Rogl, Martijn Marsman
    Physical Review B Condensed Matter 72, 054440 (2005)
    By an ab initio density functional approach the structural and phase stability, electronic and magnetic properties, elastic constants, phonon dispersion, and defect formation of the Laves-phase compound ZrMn₂ for the C15, C14, and C36 crystal structures were investigated. In order to study the...

2004

  1. H Sano, G Mizutani, Walter Wolf, Raimund Podloucky
    Physical Review B Condensed Matter 70, 125411 (2004)
    Optical second harmonic (SH) response of rutile TiO₂(110) surface was studied by the self-consistent full potential linearized augmented plane-wave method within the local-density approximation. The calculated SH response of the relaxed surface agrees with the measured SH intensity as a function of...
  2. Yue Qi, Louis Hector Jr
    Physical Review B Condensed Matter 69, 235401 (2004)
    Using a first-principles methodology, we investigated the effect of diamond surface termination on the work of separation ( W sep) , interface geometry, bond character, and adhesive transfer of three Al/diamond interfaces, viz., Al(111)/C(111)-1×1, Al(111)/C(111)-2×1 and Al(111)/C(111)-1×1:H. Bond...
  3. J. F Herbst, Louis Hector Jr
    Applied Physics Letters 85(16), 3465 (2004)
    We have investigated the energetics of hydrogen site occupation in LaNi₅H_n (hexagonal P63mc structure) and LaCo₅H_n (orthorhombic Cmmm structure) via calculation of the site-dependent enthalpies of hydride formation ΔH. For each structure ΔH was determined for a broad variety of hydrogen...
  4. JR Gladden, Jin H So, J. D Maynard, Paul Saxe, Yvon Le Page
    Applied Physics Letters 85(3), 392 (2004)
    Ab initio calculations of the basic properties of solids have advanced significantly, and it is now possible to simply access a crystal structure database, and from the given constituent atoms and their positions, calculate reasonably accurate values for elastic constants and thermomechanical...
  5. Wolfgang Bergermayer, Hannes Schweiger, Erich Wimmer
    Physical Review B Condensed Matter 69, 195409 (2004)
    The oxygen coverage, structure, and thermodynamic stability of (0001) surfaces of Fe2O3 (hematite) as a function of temperature and oxygen pressure are investigated by ab initio density functional theory with the generalized gradient approximation. Spin-polarized total energy and force calculations...
  6. L E Ramos, J Furthmüller, and F Bechstedt
    Phys. Rev. B 69, 085102 (2004)
    Band structures and dielectric functions are calculated using density-functional theory and local-density approximation for three β-cristobalite modifications of SiO₂ with space-group symmetries Fd3m, I4¯2d, and P213. Quasiparticle corrections for the Kohn-Sham eigenvalues are determined in a GW...
  7. A Rohrbach, J Hafner, and G Kresse
    Phys. Rev. B 69, 075413 (2004)
    It is well known that the physical properties of some transition-metal compounds (mostly oxides) are strongly affected by intra-atomic correlations. Very recently, investigations of the adsorption of small molecules such as CO on the surfaces of transition-metal oxides have led to rather surprising...
  8. A Rohrbach, J Hafner, and G Kresse
    Phys. Rev. B 70, 125426 (2004)
    We present a detailed ab initio investigation of the stability, the structural, electronic, and magnetic properties of the (0001) surfaces of hematite (Fe₂O₃) and chromia or eskolaite (Cr₂O₃). Strong electron correlation effects not included in a density-functional description are described by a...
  9. G Rollmann, A Rohrbach, P Entel, and J Hafner
    Phys. Rev. B 69, 165107 (2004)
    Rhombohedral α-Fe₂O₃ has been studied by using density-functional theory (DFT) and the generalized gradient approximation (GGA). For the chosen supercell all possible magnetic configurations have been taken into account. We find an antiferromagnetic ground state at the experimental volume. This...

2003

  1. T Demuth, X Rozanska, L Benco, J Hafner, A. van Santen, and H Toulhoat
    J. Catalysis 214, 68 (2003)
    The skeletal isomerization of a 2-pentene molecule catalyzed by acidic ZSM-22 was investigated by ab initio DFT studies. Two different scenarios proposed in the literature were tested. First a reaction including an alkyl shift was considered: a methyl or ethyl group is detached from the carbenium...
  2. GA Young, Jr, R Najafabadi, W Strohmayer, DG Baldrey, WL Hamm, J Harris, J Sticht and Erich Wimmer
    Technical Report OSTI 821509
    Atomistic modeling was used to investigate the effects of impurity elements on the metallurgy, irradiation embrittlement, and environmentally assisted cracking of nickel-base alloys. Calculations were performed via ab initio atomistic modeling on a nickel Σƒ5 {001} twist grain boundary. A Griffith-...
  3. A Rohrbach, J Hafner and G Kresse
    J. Phys.: Condens. Matter 15, 979 (2003)
    Density-functional studies of structural and electronic properties of transition-metal sulfides formed by 3d transition metals, based on the local spin-density approximation and including non-local corrections to the exchange–correlation functional (generalized gradient approximation), have...

2002

  1. Emeric Bourasseau, Philippe Ungerer, Anne Boutin
    Journal of Physical Chemistry B 106(21), 5483 (2002)
    To predict equilibrium properties of cyclic alkanes using the Gibbs ensemble Monte Carlo method (GEMC), a new transfer move is proposed to sample the configuration space with efficiency. This new method, called reservoir bias Monte Carlo, consists of adapting the reservoir bias insertion in the...
  2. Walter Wolf, Peter Herzig
    Physical Review B Condensed Matter 66, 224112 (2002)
    The crystallographic structure of switchable mirror material YD₃ is still under debate. Aiming at a final structure assessment, currently considered structure models of P-3c1 , P63cm and P63 symmetry are studied by means of ab initio methods. The relative stability of these candidate structures is...
  3. Yvon Le Page, Paul Saxe
    Physical Review B Condensed Matter 65, 104104 (2002)
    A symmetry-general approach for the least-squares, therefore precise, extraction of elastic coefficients for strained materials is reported. It analyzes stresses calculated ab initio for properly selected strains. The problem, its implementation, and its solution strategy all differ radically from a...
  4. Yvon Le Page, Paul Saxe, John Rodgers
    Acta Crystallographica Section B 58(3), 349-357 (2002)
    The timely integration of crystal structure databases, such as CRYSTMET, ICSD etc., with quantum software, like VASP, OresteS, ElectrA etc., allows ab initio cell and structure optimization on existing pure-phase compounds to be performed seamlessly with just a few mouse clicks. Application to the...
  5. M Marsman and J Hafner
    Phys. Rev. B 66, 224409 (2002)
    It is by now well established that in antiferromagnetic γ-Fe, stabilized in the form of precipitates in a Cu matrix or by epitaxial growth on an appropriate substrate, magnetic and/or crystalline symmetries are broken. Little is known, however, on the physical effects driving the symmetry reduction...
  6. Yvon Le Page, Paul Saxe, John Rodgers
    phys. stat. sol. (b) 229, 1155 (2002)
    Ab-initio stiffness values were computed in an automated way for two trigonal reference materials: dextro low quartz and calcite with respective space groups P3₂21 and R-3c. Both were computed in their IRE settings, namely with r faces indexed {10-11} for right-quartz and with obverse setting of...
  7. H Sano, G Mizutani, W Wolf, and R Podloucky
    Phys. Rev. B 66, 195338 (2002)
    The linear and nonlinear optical susceptibilities of unreconstructed and reconstructed (2×1) Si(111) clean and hydrogen covered surfaces were studied by application of an ab initio approach, namely the self-consistent full potential linearized augmented plane-wave method within the local-density...

2001

  1. Bruce E. Eichinger, Erich Wimmer, Jannie Pretorius
    Macromolecular Symposia 171(1), 45-56 (2001)
    The λ-transition of elemental sulfur occurring at about 159°C has long been associated with the conversion of cyclic S8 rings (c-S8) to amorphous polymer (a-S) via a ring opening polymerization. Here we demonstrate, with the use of both density functional and Hartree-Fock quantum mechanical...
  2. Clint B Geller, Walter Wolf, S Picozzi, Alessandra Continenza, R Asahi, W Mannstadt, A J Freeman, Erich Wimmer
    Applied Physics Letters 79(3), 368-370 (2001)
    Accurate band structures of binary semiconductors AB (A = Al, Ga, In and B = P, As, Sb) and selected ternary III–V semiconductors were calculated using an all-electron screened exchange approach within the full potential linearized augmented plane-wave method. Fundamental band gaps and Γ–L and Γ–X...
  3. Hervé Toulhoat
    US Patent 6799089, (2001)
    doi:
    For estimating a property of use, for example the activity of a catalyst or the ability to hold a ratio-element in a solid mineral matrix, or a material M.sub.AB whose active element is AB, there are used a descriptor D.sub.AB of the chemical bond between A and B, which has the dimension of an...
  4. Veronique Lachet, S Buttefey, A Boutin, Alain Fuchs
    Physical Chemistry Chemical Physics 3(1), 80-86 (2001)
    Grand canonical ensemble Monte Carlo simulations of the adsorption properties of several model faujasite zeolites were performed using the statistical bias method. The results enable a better understanding of the effect of cation exchange in the selective adsorption of binary mixtures of para- and...
  5. Yvon Le Page, Paul Saxe
    Physica B: Physics of Condensed Matter 307, 191 (2001)
    The structure of orthorhombic gallium was first determined in 1933 in the space group Cmca. The recent crystal structure literature also consistently uses this setting. The ab initio stiffness coefficients calculated from this crystal structure are: C₁₁=88, C₁₂=29, C₁₃=34, C₂₂=116, C₂₃=24, C₃₃=98, C₄₄=...
  6. Yvon Le Page, Paul Saxe
    Physical Review B Condensed Matter 63, 174103 (2001)
    A symmetry-general scheme for the simultaneous least-squares extraction of the elastic coefficients and of the residual strain components from ab initio total energy calculations on crystal structure models of materials is proposed. It is quite efficient and avoids error propagation. An appropriate,...
  7. S Parthiban, G de Oliveira, and J M L Martin
    J. Phys. Chem. A 105, 895 (2001)
    The energetics of the gas-phase SN2 reactions Y⁻ + CH₃X → CH₃Y + X⁻ (X,Y = F,Cl,Br), were studied using (variants on) the recent W1 and W2 ab initio computational thermochemistry methods. These calculations involve CCSD and CCSD(T) coupled cluster methods, basis sets of up to spdfgh quality,...
  8. B J Lynch and D G Truhlar
    J. Phys. Chem. A 105, 2936 (2001)
    We compare hybrid Hartree−Fock density-functional theory to ab initio approaches for locating saddle point geometries and calculating barrier heights on a Born−Oppenhiemer potential energy surface. We located reactant, product, and saddle point stationary points for 22 reactions by the MP2 and...
  9. A A Valladares, F Alvarez, Z Liu, J Sticht, and J Harris
    Eur. Phys. J. B 22, 443–453 (2001)
    We propose a method to simulate a-Si and a-Si:H using an ab initio approach based on the Harris functional and thermally-amorphisized periodically-continued cells with at least 64 atoms. Hydrogen incorporation was achieved via diffusive addition. In preparing samples that may simulate the...

2000

  1. J Delhommelle, C Tschirwitz, Philippe Ungerer, G Granucci, P Millie, D Pattou, Alain Fuchs
    Journal of Physical Chemistry B 104(19), 4745-4753 (2000)
    An extension of the anisotropic united atoms model is proposed for thiols and sulfides. A complete derivation of the nonbonded parameters is performed with the aim of obtaining a transferable force field. The electrostatic part of the intermolecular potential is represented by a set of atomic...
  2. S Picozzi, A Continenza, R Asahi, W Mannstadt, A J Freeman, Walter Wolf, Erich Wimmer, Clint B Geller
    Physical Review B Condensed Matter 61(7), 4677 (2000)
    Quasiparticle electronic band structures for ternary InGaAs and InGaSb systems, modeled by a luzonite structure, have been obtained using the screened-exchange local-density approximation approach. We focus our attention on energy transitions relevant for the electron-hole pair lifetime and, in...
  3. JR Hill, AR Minihan, Erich Wimmer, CJ Adams
    Physical Chemistry Chemical Physics 2(18), 4255-4264 (2000)
    Computer simulations of the water adsorption isotherm of zeolite Na-MAP have been performed. Both grand canonical molecular dynamics and a combination of Monte Carlo calculations and lattice relaxations (pseudodynamic simulations) have been used to account for the lattice dynamics of the zeolite...
  4. JR Hill, JA Stuart, AR Minihan, Erich Wimmer, CJ Adams
    Physical Chemistry Chemical Physics 2(18), 4249-4254 (2000)
    Periodic density functional calculations on zeolite Na-MAP are presented. These calculations used a preliminary model obtained from X-ray powder diffraction as starting point and fully optimized the atom positions within the unit cell. It is shown that the structure obtained in the calculation...
  5. D Hobbs, G Kresse, and J Hafner
    Phys. Rev. B 62, 11556–11570 (2000)
    Spin-polarized calculations in solids have generally been confined to a global quantization axis to simplify both the theoretical model and its implementation in self-consistent codes. This approximation is justified as many materials exhibit a collinear magnetic order. However, in recent years...
  6. E Wimmer and W Wolf
    Materials Science in Semiconductor Processing 3, 3–11 (2000)
    The control of materials properties and their relation to the manufacturing processes are central in achieving better performance and lower manufacturing costs of microelectronic devices. To this end, ab initio methods can contribute unique information about materials properties and processes where...

1999

  1. B Hammer, L B Hansen, Jens K Nørskov
    Physical Review B Condensed Matter 59(11), 7413-7421 (1999)
    A simple formulation of a generalized gradient approximation for the exchange and correlation energy of electrons has been proposed by Perdew, Burke, and Ernzerhof (PBE) [Phys. Rev. Lett. 77, 3865 (1996)]. Subsequently Zhang and Yang [Phys. Rev. Lett. 80, 890 (1998)] have shown that a slight...
  2. B Neubauer, Bernard Tavitian, A Boutin, Philippe Ungerer
    Fluid Phase Equilibria 161(1), 45 (1999)
    We have employed Monte Carlo simulation in the NPT ensemble to determine the molar volume and the compressibility factor of naturally occurring hydrocarbon gas mixtures. The simulation results were compared to experimental data as well as to predictions based on both the Peng–Robinson and AGA 8...
  3. Georg Kresse, D Joubert
    Physical Review B Condensed Matter 59(3), 1758 (1999)
    The formal relationship between ultrasoft (US) Vanderbilt-type pseudopotentials and Blöchl’s projector augmented wave (PAW) method is derived. It is shown that the total energy functional for US pseudopotentials can be obtained by linearization of two terms in a slightly modified PAW total energy...
  4. Veronique Lachet, Anne Boutin, Bernard Tavitian, Alain Fuchs
    Langmuir 15(25), 8678-8685 (1999)
    The properties of p-xylene and m-xylene adsorbed in NaY and KY faujasites have been studied by grand canonical Monte Carlo simulation. Biased particle insertions and deletions were implemented to allow the computation of equilibrium adsorption isotherms of such complex systems. This work is based...
  5. W. Kohn
    Rev. Modern Phys. 71, S59 (1999)
    When the 20th century opened, the fields of crystallography, metallurgy, elasticity, magnetism, etc., dealing with diverse aspects of solid matter, were largely autonomous areas of science. Only in the 1940s were these and other fields consolidated into the newly named discipline of "solid...
  6. M Ernzerhof and G E Scuseria
    J. Chem. Phys. 110, 5029 (1999)
    In order to discriminate between approximations to the exchange-correlation energy E<sub>XC</sub>[ρ↑,ρ↓], we employ the criterion of whether the functional is fitted to a certain experimental data set or if it is constructed to satisfy physical constraints. We present extensive test...

1998

  1. T Spyriouni, I Economou, D Theodorou
    Physical Review Letters (1998) vol. 80 (20) pp. 4466-4469
    A new iterative Monte Carlo simulation scheme is presented for the efficient prediction of fluid­ phase equilibria of mixtures containing long chain molecules. Using realistic molecular potentials, the high-pressure vapor-liquid and liquid-liquid equilibria of binary mixtures of ethane or ethylene...
  2. W F van Gunsteren and A E Mark
    J. Chem. Phys. 108, 6109 (1998)
    How the results obtained by computer simulation of molecular systems can be validated is considered. The overall quality of the simulated properties of a molecular system will depend on (i) the quality of the theory or model, (ii) the accuracy of the interatomic interaction function or force field...

1997

  1. K Parlinski, ZQ Li, Yoshiyuki Kawazoe
    Physical Review Letters 78(21), 4063-4066 (1997)
    A direct approach to calculate the phonon dispersion using an ab initio force constant method is introduced. The phonon dispersion and structural instability of cubic ZrO₂ are found using a supercell method in the local-density approximation. The force constants are determined from the Hellmann-...
  2. J C Grossman and L Mitas
    Phys. Rev. Lett. 79, 4353 (1997)
    We demonstrate that the quantum Monte Carlo (QMC) methodology (i) provides barrier heights and heats of formation within ∼0.05eV of experimental values, (ii) confirms recent measurements for the ring inversion of cyclo-octatetraene, and (iii) enables us to predict quantities not yet measured....

1996

  1. Georg Kresse, Jürgen Furthmüller
    Physical Review B Condensed Matter 54(16), 11169 (1996)
    We present an efficient scheme for calculating the Kohn-Sham ground state of metallic systems using pseudopotentials and a plane-wave basis set. In the first part the application of Pulay’s DIIS method (direct inversion in the iterative subspace) to the iterative diagonalization of large matrices...

1991

  1. J Trinkhaus and K Dennis
    Psychological Reports 69, no. 3 (December 1991): 1165–1166
    TRINKAUS, JOHN, and KAREN DENNIS. “Taste preference for brussels sprouts: an informal look.” Psychological Reports 69, no. 3 (December 1991): 1165–1166.

1989

  1. R. G. Parr and W. Yang
    New York: Oxford University Press
    doi:

1977

  1. S L Dole, O Hunter Jr., and C J Wooge
    J. Am. Chem. Soc 60, 488 (1977)
    The Young's and shear moduli of polycrystalline monoclinic hafnium oxide were determined by the sonic resonance method at room temperature as a function of volume fraction porosity. The Spriggs equation empirically described the data and the zero porosity moduli as 283.6 GN/m² and 109.2 GN/m²...

1976

  1. K Yvon, W Jeitschko, E Parthé
    J. Appl. Cryst. 10, 73 (1977)
    A computer program has been written with the aim of calculating powder patterns without the use of crystallographic tables. This has been achieved by deriving all symmetry information such as general equivalent positions from the Hermann-Mauguin space-group symbols, by calculating automatically the...

Full Text and Download

You can download (most) of the presentations and publications.

Please log in as a customer or contact our sales team.