FIRST PRINCIPLES CALCULATIONS OF THE STRUCTURAL AND THERMAL PROPERTIES OF THE ROCKSALT CaX (X = S, Se, Te)

Abstract

We have investigated the structural and elastic behaviour of the rocksalt CaX (X = S, Se, Te) crystals by means of first principles calculations using the full-potential augmented plane wave (FP-LAPW) method. Ground state properties such as the lattice parameters a, bulk modulus B, its pressure derivative B’ and the elastic parameters (C11, C12, and C44), have been directly calculated and compared to previous experimental and theoretical results when available. Thermal properties, including the linear and cubic expansion coefficients and the heat capacity, have been estimated using a quasi-harmonic Debye model. To our knowledge this is the first quantitative theoretical prediction of thermal properties for these compounds and still awaits experimental confirmation.