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Phase diagram of MgO from density-functional theory and molecular-dynamics simulations

Strachan, Alejandro and Çağin, Tahir and Goddard, William A., III (1999) Phase diagram of MgO from density-functional theory and molecular-dynamics simulations. Physical Review B, 60 (22). pp. 15084-15093. ISSN 0163-1829. doi:10.1103/PhysRevB.60.15084.

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We use first-principles methods (no empirical parameters) to establish the phase diagram for the B1(NaCl), B2(CsCl), and liquid phases of MgO. We used density-functional theory with the generalized gradient approximation to predict the equation-of-state [volume versus pressure (V(P))] at 0 K for MgO in the low-density B1 (NaCl) phase and the high-density B2 (CsCl) phase. We find a pressure-induced phase transition at P=400 GPa. We then fitted an MS-Q type force field (FF) to the quantum results. This FF, denoted as qMS-Q FF, was then used in molecular dynamics (MD) simulations to investigate the phase coexistence curves of the B1-B2 and B1-liquid phases. This leads to a first-principles phase diagram for MgO for pressures up to 500 GPa and temperatures up to 8000 K. The accuracy of the fit of the qMS-Q FF to the quantum mechanics validates the functional form of the qMS-Q FF in which the charges are obtained from charge equilibration (QEq) and the nonelectrostatic forces are described with simple two-body Morse potentials. Such qMS-Q FF using no empirical data should be useful for MD or Monte Carlo simulations of many other materials.

Item Type:Article
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URLURL TypeDescription
Strachan, Alejandro0000-0002-4174-9750
Çağin, Tahir0000-0002-3665-0932
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 1999 The American Physical Society. Received 13 May 1999. We thank Dr. Ersan Demiralp for useful discussions. This research was funded by a grant from DOE-ASCI. A.S. acknowledges financial support from FOMEC (Argentina). The facilities of the MSC are also supported by grants from NSF (CHE 95-22179), ARO (MURI), ARO (DURIP), BP Chemical, Exxon, Dow Chemical, Owens-Corning, Avery Dennison, Chevron Petroleum Technology Co., Asahi Chemical, Chevron Chemical Co., Chevron Research Technology Co., and Beckman Institute.
Funding AgencyGrant Number
Department of Energy (DOE)UNSPECIFIED
Fondo para el Mejoramiento de la Calidad (FOMEC)UNSPECIFIED
NSFCHE 95-22179
Army Research Office (ARO)UNSPECIFIED
Dow Chemical CompanyUNSPECIFIED
Chevron Petroleum Technology Co.UNSPECIFIED
Chevron Chemical Co.UNSPECIFIED
Chevron Research TechnologyUNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Issue or Number:22
Record Number:CaltechAUTHORS:STRAprb99
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ID Code:2159
Deposited By: Archive Administrator
Deposited On:12 Mar 2006
Last Modified:08 Nov 2021 19:45

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