Ab Initio thermodynamic and elastic properties of alkaline-earth metals and their hydrides

L. G. Hector, Jr., J. F. Herbst, W. Wolf, P. Saxe, and G. Kresse

Phys. Rev. B 76, 014121 – Published 27 July 2007

Abstract

A systematic investigation of the alkaline earth hydrides $Be H_{2}$ , $Mg H_{2}$ , $Ca H_{2}$ , $Sr H_{2}$ , $Ba H_{2}$ , the corresponding deuterides, and their antecedent metals is reported. We calculate lattice parameters, electronic and vibrational energies, enthalpies of formation at 0 and $298 K$ , components of the elasticity tensor, $C_{i j}$ , and polycrystalline moduli based on the Hill criteria using density functional theory. Components of the Born effective charge tensors and phonon spectra are also computed for each hydride. We critically compare results obtained via the local density and generalized gradient approximations for the exchange-correlation energy functional. The volume dependence of the zero point energy is also investigated for Be and $Be H_{2}$ .