title: Ab initio refinement of the thermal equation of state for bcc tantalum: the effect of bonding on anharmonicity.
abstract: We report a detailed ab initio study for body-centered-cubic (bcc) Ta within the framework of the quasiharmonic approximation (QHA) to refine its thermal equation of state and thermodynamic properties. Based on the excellent agreement of our calculated phonon dispersion curve with experiment, the accurate thermal equations of state and thermodynamic properties are well reproduced. The thermal equation of state (EOS) and EOS parameters are considerably improved in our work compared with previous results by others. Furthermore, at high temperatures, the excellent agreement of our obtained thermal expansion and Hugoniot curves with experiments greatly verifies the validity of the quasiharmonic approximation at higher temperatures. It is known that pressure suppresses the vibrations of atoms from their equilibrium positions, i.e. the bondings among atoms are strengthened by pressure; for the same temperature, anharmonicity becomes less important at high pressure. Thus the highest valid temperature of the QHA can be reasonably extended to the larger range.
authors.affiliation: Laboratory for Shock Wave and Detonation Physics Research, Institute of Fluid Physics, PO Box 919-102, 621900 Mianyang, Sichuan, People's Republic of China. Institute of Atomic and Molecular Physics, College of Physical Science and Technology, Sichuan University, Chengdu 610065, People's Republic of China.
authors.forename: Zhong-Li
authors.initials: ZL
authors.lastname: Liu
authors.forename: Ling-Cang
authors.initials: LC
authors.lastname: Cai
authors.forename: Xiang-Rong
authors.initials: XR
authors.lastname: Chen
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.forename: Fu-Qian
authors.initials: FQ
authors.lastname: Jing