Issue
Europhys. Lett.
Volume 74, Number 1, April 2006
Page(s) 83 - 88
Section Condensed matter: structural, mechanical and thermal properties
DOI http://dx.doi.org/10.1209/epl/i2005-10499-9
Published online 22 February 2006
Europhys. Lett., 74 (1), pp. 83-88 (2006)
DOI: 10.1209/epl/i2005-10499-9

Structure of barium in three phases under pressure

F. Jona and P. M. Marcus

Department of Materials Science and Engineering, State University of New York Stony Brook, NY 11794-2275, USA


received 5 December 2005; accepted in final form 3 February 2006
published online 22 February 2006

Abstract
A first-principles calculation of the structure of barium under pressure was done with a procedure which finds the equilibrium structure by minimizing the Gibbs free energy at zero temperature with respect to structure at each pressure. The calculated structures agree with measurements at the 1% level in three phases, Ba I (body-centered cubic), Ba II and V (hexagonal close-packed), over a range of pressure from 0 to 900 kbar. The fit to experiment is closer than that of two previous calculations, one of which used molecular dynamics under an applied stress to find equilibrium structure, and the other minimized the energy at constant volume. Hexagonal close-packed barium is shown to be metastable in the pressure range of the incommensurate Ba IV phase.

PACS
61.66.Bi - Elemental solids.
64.70.Kb - Solid-solid transitions.
71.15.Nc - Total energy and cohesive energy calculations.

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