The Experts below are selected from a list of 20445 Experts worldwide ranked by ideXlab platform
Hideki Tanaka - One of the best experts on this subject based on the ideXlab platform.
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On the Debye-Waller factor of hexagonal ice: a computer simulation study.
Journal of the American Chemical Society, 2002Co-Authors: Hideki Tanaka, Udayan MohantyAbstract:We investigate by molecular dynamics (MD) simulations the temperature dependence of the Debye−Waller (DW) factor of hexagonal ice with 25 different proton-disordered configurations. Each initial configuration is composed of 288 water molecules with no net dipole moment. The intermolecular interaction of water is described by TIP4P potential. Each production run of the simulation is 15 ns or longer. We observe a change in slope of the DW factor around 200 K, which cannot be explained within the framework of either classical or quantum harmonic approximation. Configurations generated by MD simulations are subjected to the steepest descent Energy minimization. Analysis of the Local Energy Minimum structures reveals that water molecules above 200 K jump to other lattice sites via some Local Energy Minimum structures which contain some water molecules sitting on the locations other than the lattice sites. As time evolves, these defect molecules move back and forth to the lattice sites yielding defect-free stru...
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A molecular dynamics study of the connectivity of water molecules in supercooled states
Physical Chemistry Chemical Physics, 2000Co-Authors: Hideki TanakaAbstract:We examined the distributions of four-coordinated supercooled water molecules in two state points where the densities differ considerably. It is found that although the coordination numbers are all four in Local Energy Minimum structures free from thermal excitation, the magnitude of the connectivity of tetrahedrally coordinated molecules differs significantly between two supercooled states. We also investigated the thermodynamic properties of liquids composed of two kinds of deformed water molecules having wider bond angles in order to compare the properties of these liquids with those of a realistic water model.
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Fluctuation of Local order and connectivity of water molecules in two phases of supercooled water
Physical Review Letters, 1998Co-Authors: Hideki TanakaAbstract:We investigate the fluctuations of coordination numbers and the spatial correlations of imperfectly coordinated water molecules in two phases of supercooled water. It is found, although the average coordination numbers are 4 in Local Energy Minimum structures of both phases, that the magnitude of the fluctuation differs significantly between two phases. Connectivity of water molecules whose first and second neighbors are also perfectly (four-) coordinated is examined. It is revealed that such Locally ordered water molecules spread over the entire system in the low density liquid phase whereas those molecules form only small size clusters in the high density liquid water phase.
Christian Elsasser - One of the best experts on this subject based on the ideXlab platform.
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theoretical investigation of 110 generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
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Theoretical investigation of {110} generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
Pierre Hirel - One of the best experts on this subject based on the ideXlab platform.
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theoretical investigation of 110 generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
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Theoretical investigation of {110} generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
Matous Mrovec - One of the best experts on this subject based on the ideXlab platform.
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theoretical investigation of 110 generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
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Theoretical investigation of {110} generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
P. Marton - One of the best experts on this subject based on the ideXlab platform.
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theoretical investigation of 110 generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.
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Theoretical investigation of {110} generalized stacking faults and their relation to dislocation behavior in perovskite oxides
Acta Materialia, 2010Co-Authors: Pierre Hirel, P. Marton, Matous Mrovec, Christian ElsasserAbstract:Abstract Studies of generalized stacking fault Energy surfaces, or γ-surfaces, provide a convenient and efficient source of information on possible dislocation dissociation mechanisms and favorable glide systems. We carried out an extensive theoretical investigation of the {1 1 0}γ-surface for three technologically important perovskite oxides SrTiO3, BaTiO3, and PbTiO3. The calculations were performed using both a highly accurate first-principles density functional theory approach and simple empirical interatomic potentials. The main characteristic features common to all {1 1 0}γ-surfaces are the low Energy path along the 〈 1 1 ¯ 0 〉 direction and the existence of a single Local Energy Minimum along this path. This Minimum corresponds to an antiphase boundary that has been observed experimentally in dissociated dislocation cores in various perovskites. The Energy profiles obtained using the empirical potentials agree qualitatively well with the first-principles results but there are significant quantitative discrepancies. This comparison provides a valuable insight into the quality and limitations of empirical potentials for atomistic simulations of dislocations and other extended defects in these materials.