Ab initio calculations of structural, elastic, and thermodynamic properties of HoX (X=N, O, S and Se)

We investigated the structural, elastic, and thermodynamic properties of HoX (X= N, O, S and Se), a series of pnictides and chalcogenides based on the rare-earth metal, Ho. These properties were studied by first-principles calculations of the total energy using the full-potential linearized augmented plane wave method. Calculations were performed within the generalized gradient approximation for the exchange correlation potential. Structural parameters, namely, lattice parameter, bulk modulus and its pressure derivate, and cohesive energy with and without spin polarization of the structures NaCl, CsCl, ZB, tetragonal crystal, WC, NiAs, PbO, and wurtzite were determined. Elastic constants were derived from the stress–strain relation at 0 K. We also determined the thermodynamics properties for HoX through the quasiharmonic Debye model. The temperature and pressure variation of the volume, bulk modulus, thermal expansion coefficient, heat capacities, and Debye temperature at various pressures (0–50 GPa) and temperatures (0–1500 K) were predicted.