Ionic solids at elevated temperatures and high pressures: MgF2

A combination of periodic Hartree-Fock theory, quasiharmonic lattice dynamics, and molecular dynamics is used to study the behavior of MgF2 at elevated temperatures and/or high pressures. Particular attention is paid to the pressure-induced transition from the rutile to the fluorite structure in vie...

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Autores principales: Barrera, G.D., Taylor, M.B., Allan, N.L., Barron, T.H.K., Kantorovich, L.N., Mackrodt, W.C.
Formato: JOUR
Acceso en línea:http://hdl.handle.net/20.500.12110/paper_00219606_v107_n11_p4337_Barrera
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_00219606_v107_n11_p4337_Barrera2023-10-03T14:23:54Z Ionic solids at elevated temperatures and high pressures: MgF2 Barrera, G.D. Taylor, M.B. Allan, N.L. Barron, T.H.K. Kantorovich, L.N. Mackrodt, W.C. A combination of periodic Hartree-Fock theory, quasiharmonic lattice dynamics, and molecular dynamics is used to study the behavior of MgF2 at elevated temperatures and/or high pressures. Particular attention is paid to the pressure-induced transition from the rutile to the fluorite structure in view of earlier theoretical estimates of the transition pressure, which differ widely. It is shown that previously reported potentials obtained by fitting to empirical data fail to reproduce thermodynamic properties. To rectify this, a new set of consistent two-body potentials has been derived from ab initia periodic Hartree-Fock calculations. Lattice dynamics calculations in the quasiharmonic approximation based on these potentials has been used to study the two phases of MgF2 at high T and P. The resulting transition pressure and that obtained directly from Hartree-Fock calculations in the static limit are both ≤30 GPa, which is close to the experimental value but appreciably lower than a previous molecular dynamics value of over 130 GPa. The variation of quantities such as (∂P/∂T)v which play a central role in the formulation of approximate equations of state is also considered. © 1997 American Institute of Physics. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_00219606_v107_n11_p4337_Barrera
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description A combination of periodic Hartree-Fock theory, quasiharmonic lattice dynamics, and molecular dynamics is used to study the behavior of MgF2 at elevated temperatures and/or high pressures. Particular attention is paid to the pressure-induced transition from the rutile to the fluorite structure in view of earlier theoretical estimates of the transition pressure, which differ widely. It is shown that previously reported potentials obtained by fitting to empirical data fail to reproduce thermodynamic properties. To rectify this, a new set of consistent two-body potentials has been derived from ab initia periodic Hartree-Fock calculations. Lattice dynamics calculations in the quasiharmonic approximation based on these potentials has been used to study the two phases of MgF2 at high T and P. The resulting transition pressure and that obtained directly from Hartree-Fock calculations in the static limit are both ≤30 GPa, which is close to the experimental value but appreciably lower than a previous molecular dynamics value of over 130 GPa. The variation of quantities such as (∂P/∂T)v which play a central role in the formulation of approximate equations of state is also considered. © 1997 American Institute of Physics.
format JOUR
author Barrera, G.D.
Taylor, M.B.
Allan, N.L.
Barron, T.H.K.
Kantorovich, L.N.
Mackrodt, W.C.
spellingShingle Barrera, G.D.
Taylor, M.B.
Allan, N.L.
Barron, T.H.K.
Kantorovich, L.N.
Mackrodt, W.C.
Ionic solids at elevated temperatures and high pressures: MgF2
author_facet Barrera, G.D.
Taylor, M.B.
Allan, N.L.
Barron, T.H.K.
Kantorovich, L.N.
Mackrodt, W.C.
author_sort Barrera, G.D.
title Ionic solids at elevated temperatures and high pressures: MgF2
title_short Ionic solids at elevated temperatures and high pressures: MgF2
title_full Ionic solids at elevated temperatures and high pressures: MgF2
title_fullStr Ionic solids at elevated temperatures and high pressures: MgF2
title_full_unstemmed Ionic solids at elevated temperatures and high pressures: MgF2
title_sort ionic solids at elevated temperatures and high pressures: mgf2
url http://hdl.handle.net/20.500.12110/paper_00219606_v107_n11_p4337_Barrera
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AT kantorovichln ionicsolidsatelevatedtemperaturesandhighpressuresmgf2
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