The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
D D Klug - One of the best experts on this subject based on the ideXlab platform.
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Molecular dynamics simulations of binary structure H hydrogen and methyl-tert-butylether clathrate hydrates.
The Journal of chemical physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:Binary structure H (sH) hydrogen and methyl-tert-butylether (MTBE) clathrate hydrates are studied with molecular dynamics simulations. Simulations on a 3 x 3 x 3 sH unit cell with up to 4.7 mass % hydrogen gas are run at pressures of 100 bars and 2 kbars at 100 and 273 K. For the small and medium cages of the sH unit cell, H2 guest molecule occupancies of 0, 1 (single occupancy), and 2 (double occupancy) are considered with the MTBE molecule occupying all of the large cages. An increase of the small and medium cage occupancies from 1 to 2 leads to a jump in the unit cell volume and Configurational Energy. Calculations are also set up with 13, 23, and 89 of the MTBE molecules in the large cages replaced by sets of three to six H2 molecules, and the effects on the Configurational Energy and volume of the simulation cell are determined. As MTBE molecules are replaced with sets of H2 guests in the large cages, the Configurational Energy of the unit cell increases. At the lower temperature, the Energy and volume of the clathrate are not sensitive to the number of hydrogen guests in the large cages; however, at higher temperatures the repulsions among the H2 guest molecules in the large cages cause an increase in the system Energy and volume.
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Molecular dynamics simulations of binary structure H hydrogen and methyl-tert-butylether clathrate hydrates.
Journal of Chemical Physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:Binary structure H (sH) hydrogen and methyl-tert-butylether (MTBE) clathrate hydrates are studied with molecular dynamics simulations. Simulations on a 3×3×3sH unit cell with up to 4.7mass% hydrogen gas are run at pressures of 100bars and 2kbars at 100 and 273K. For the small and medium cages of the sH unit cell, H2 guest molecule occupancies of 0, 1 (single occupancy), and 2 (double occupancy) are considered with the MTBE molecule occupying all of the large cages. An increase of the small and medium cage occupancies from 1 to 2 leads to a jump in the unit cell volume and Configurational Energy. Calculations are also set up with 1∕3, 2∕3, and 8∕9 of the MTBE molecules in the large cages replaced by sets of three to six H2 molecules, and the effects on the Configurational Energy and volume of the simulation cell are determined. As MTBE molecules are replaced with sets of H2 guests in the large cages, the Configurational Energy of the unit cell increases. At the lower temperature, the Energy and volume of t...
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molecular dynamics simulations of binary structure ii hydrogen and tetrahydrofurane clathrates
Journal of Chemical Physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:The binary structure II hydrogen and tetrahydrofurane (THF) clathrates are studied with molecular-dynamics simulations. Simulations are done at pressures of 120 and 1.013bars for temperatures ranging from 100to273K. For the small cages of the structure II unit cell, H2 guest molecule occupancies of 0, 16 (single occupancy), and 32 (double occupancy) are considered. THF occupancies of 0–8 in the large cages are studied. For cases in which THF does not occupy all large cages in a unit cell, the remaining large cages can be occupied with sets of four H2 guest molecules. The unit-cell volumes and Configurational energies are compared in the different occupancy cases. Increasing the small cage occupancy leads to an increase in the unit-cell volume and thermal-expansion coefficient. Among simulations with the same small cage occupancy, those with the large cages containing 4H2 guests have the largest volumes. The THF guest molecules have a stabilizing effect on the clathrate and the Configurational Energy of th...
Helmut Dosch - One of the best experts on this subject based on the ideXlab platform.
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Topological k-space refinement of the Configurational Energy of alloys
Physical Review B, 2005Co-Authors: O. Shchyglo, V. N. Bugaev, A. Udyansky, Harald Reichert, Ralf Drautz, Helmut DoschAbstract:We present an iterative refinement procedure for the construction of $k$-space interactions in binary alloys. The procedure consists of successive steps, which refine the topological features of the $k$-space interactions and naturally incorporate long-ranging interactions. We apply this scheme to the fcc lattice and create a limited set of ordered structures, which allows us to calculate interactions at selected $k$-space points. We demonstrate that the energies of a few ab initio calculated input structures are sufficient for the construction of the relevant $k$-space interaction parameters in ${\mathrm{Cu}}_{3}\mathrm{Au}$.
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q-space Configurational Energy and short-range order in alloys with atomic size mismatch
Physical Review B, 2002Co-Authors: V. N. Bugaev, A. Udyansky, Y. Sikula, O. Shchyglo, Harald Reichert, Helmut DoschAbstract:We present a q-space method for the incorporation of long-range strain fields into the statistical thermodynamies of binary alloys with atomic size mismatch. In this approach the Configurational Energy is parametrized viaa set of potentials and generalized Kanzaki forces providing a powerful description of strain-induced many-body effects for systems with lattice distortions. We show how strain-induced interactions act on the topology of short-range-order patterns.
Saman Alavi - One of the best experts on this subject based on the ideXlab platform.
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Molecular dynamics simulations of binary structure H hydrogen and methyl-tert-butylether clathrate hydrates.
The Journal of chemical physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:Binary structure H (sH) hydrogen and methyl-tert-butylether (MTBE) clathrate hydrates are studied with molecular dynamics simulations. Simulations on a 3 x 3 x 3 sH unit cell with up to 4.7 mass % hydrogen gas are run at pressures of 100 bars and 2 kbars at 100 and 273 K. For the small and medium cages of the sH unit cell, H2 guest molecule occupancies of 0, 1 (single occupancy), and 2 (double occupancy) are considered with the MTBE molecule occupying all of the large cages. An increase of the small and medium cage occupancies from 1 to 2 leads to a jump in the unit cell volume and Configurational Energy. Calculations are also set up with 13, 23, and 89 of the MTBE molecules in the large cages replaced by sets of three to six H2 molecules, and the effects on the Configurational Energy and volume of the simulation cell are determined. As MTBE molecules are replaced with sets of H2 guests in the large cages, the Configurational Energy of the unit cell increases. At the lower temperature, the Energy and volume of the clathrate are not sensitive to the number of hydrogen guests in the large cages; however, at higher temperatures the repulsions among the H2 guest molecules in the large cages cause an increase in the system Energy and volume.
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Molecular dynamics simulations of binary structure H hydrogen and methyl-tert-butylether clathrate hydrates.
Journal of Chemical Physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:Binary structure H (sH) hydrogen and methyl-tert-butylether (MTBE) clathrate hydrates are studied with molecular dynamics simulations. Simulations on a 3×3×3sH unit cell with up to 4.7mass% hydrogen gas are run at pressures of 100bars and 2kbars at 100 and 273K. For the small and medium cages of the sH unit cell, H2 guest molecule occupancies of 0, 1 (single occupancy), and 2 (double occupancy) are considered with the MTBE molecule occupying all of the large cages. An increase of the small and medium cage occupancies from 1 to 2 leads to a jump in the unit cell volume and Configurational Energy. Calculations are also set up with 1∕3, 2∕3, and 8∕9 of the MTBE molecules in the large cages replaced by sets of three to six H2 molecules, and the effects on the Configurational Energy and volume of the simulation cell are determined. As MTBE molecules are replaced with sets of H2 guests in the large cages, the Configurational Energy of the unit cell increases. At the lower temperature, the Energy and volume of t...
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molecular dynamics simulations of binary structure ii hydrogen and tetrahydrofurane clathrates
Journal of Chemical Physics, 2006Co-Authors: Saman Alavi, John A Ripmeester, D D KlugAbstract:The binary structure II hydrogen and tetrahydrofurane (THF) clathrates are studied with molecular-dynamics simulations. Simulations are done at pressures of 120 and 1.013bars for temperatures ranging from 100to273K. For the small cages of the structure II unit cell, H2 guest molecule occupancies of 0, 16 (single occupancy), and 32 (double occupancy) are considered. THF occupancies of 0–8 in the large cages are studied. For cases in which THF does not occupy all large cages in a unit cell, the remaining large cages can be occupied with sets of four H2 guest molecules. The unit-cell volumes and Configurational energies are compared in the different occupancy cases. Increasing the small cage occupancy leads to an increase in the unit-cell volume and thermal-expansion coefficient. Among simulations with the same small cage occupancy, those with the large cages containing 4H2 guests have the largest volumes. The THF guest molecules have a stabilizing effect on the clathrate and the Configurational Energy of th...
Curt A Bronkhorst - One of the best experts on this subject based on the ideXlab platform.
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thermomechanical conversion in metals dislocation plasticity model evaluation of the taylor quinney coefficient
Acta Materialia, 2021Co-Authors: Charles K C Lieou, Curt A BronkhorstAbstract:Abstract Using a partitioned-Energy thermodynamic framework which assigns Energy to that of atomic Configurational stored Energy of cold work and kinetic-vibrational, we derive an important constraint on the Taylor-Quinney coefficient, which quantifies the fraction of plastic work that is converted into heat during plastic deformation. Associated with the two Energy contributions are two separate temperatures – the ordinary temperature for the thermal Energy and the effective temperature for the Configurational Energy. We show that the Taylor-Quinney coefficient is a function of the thermodynamically defined effective temperature that measures the atomic Configurational disorder in the material. Finite-element analysis of recently published experiments on the aluminum alloy 6016-T4 [1], using the thermodynamic dislocation theory (TDT), shows good agreement between theory and experiment for both stress-strain behavior and temporal evolution of the temperature. The simulations include both conductive and convective thermal Energy loss during the experiments, and significant thermal gradients exist within the simulation results. Computed values of the differential Taylor-Quinney coefficient are also presented and suggest a value which differs between materials and increases with increasing strain.
O. Shchyglo - One of the best experts on this subject based on the ideXlab platform.
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Topological k-space refinement of the Configurational Energy of alloys
Physical Review B, 2005Co-Authors: O. Shchyglo, V. N. Bugaev, A. Udyansky, Harald Reichert, Ralf Drautz, Helmut DoschAbstract:We present an iterative refinement procedure for the construction of $k$-space interactions in binary alloys. The procedure consists of successive steps, which refine the topological features of the $k$-space interactions and naturally incorporate long-ranging interactions. We apply this scheme to the fcc lattice and create a limited set of ordered structures, which allows us to calculate interactions at selected $k$-space points. We demonstrate that the energies of a few ab initio calculated input structures are sufficient for the construction of the relevant $k$-space interaction parameters in ${\mathrm{Cu}}_{3}\mathrm{Au}$.
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q-space Configurational Energy and short-range order in alloys with atomic size mismatch
Physical Review B, 2002Co-Authors: V. N. Bugaev, A. Udyansky, Y. Sikula, O. Shchyglo, Harald Reichert, Helmut DoschAbstract:We present a q-space method for the incorporation of long-range strain fields into the statistical thermodynamies of binary alloys with atomic size mismatch. In this approach the Configurational Energy is parametrized viaa set of potentials and generalized Kanzaki forces providing a powerful description of strain-induced many-body effects for systems with lattice distortions. We show how strain-induced interactions act on the topology of short-range-order patterns.