First-principles calculation of structural stability, lattice dynamic and thermodynamic properties of BeX (X = S, Se and Te) compounds under high pressure

Abstract

The phase transitions, lattice dynamical and thermodynamic properties of BeS, BsSe and BeTe at high pressure have been investigated with the density functional theory. The calculated equilibrium structural parameters agree well with the available experimental and theoretical values. The phase transition pressures from the zinc-blende (ZB) to the nickel arsenide (NiAs) phase of these compounds are determined. The calculated phonon dispersion curves of these compounds in ZB phase at zero pressure do not show any anomaly or instability. Dynamically, the ZB phase of BeS, BeSe and BeTe is found to be stable near transition pressures P_T. Within the quasiharmonic approximation, the thermodynamic properties including the thermal expansion coefficient, heat capacity at constant volume, heat capacity at constant pressure and entropy are predicted.

Keywords:

• lattice dynamic
• thermodynamic properties
• density functional theory

Acknowledgements

The authors acknowledge the support of the computational resources by the State Key Laboratory of Polymer Materials Engineering of China in Sichuan University.

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [grant number 11204192]; the NSAF Joint Fund Jointly set up by the National Natural Science Foundation of China and the Chinese Academy of Engineering Physics [grant number U1230201]; the National Key Laboratory Fund for Shock Wave and Detonation Physics Research of the China Academy of Engineering Physics [grant number 2012-Zhuan-08]; and the Science and Technology Development Foundation of China Academy of Engineering Physics [grant number 2013B0101002].