Elastic, electronic and crystal structure of SrH2 by the method of pseudopotentials

The pseudopotentials method is used to calculate some properties of the solid strontium hydride, SrH2, namely the structural, electronic and elastic ones. The validity of these results is tested by comparison with their equivalents calculated in CaH2. The analysis of bands structure, Mulliken's populations and density of states, has shown that SrH2 is an insulator solid, less ionic than CaH2, its band of valence is constituted primarily by the 3s(H) orbital with a weak participation of 1s(H) and 2s(H) orbitals, and its band of conduction is formed essentially by the orbital 2p(H) with a small contribution of both the 2s(H) orbital and the orbital describing the two valence electrons of the Sr atom (Ss(Sr) or Ssp(Sr)). The addition of the orbital d(Sr), on the one hand, has a remarkable effect on the distribution of electronic charges and, on the other hand, it participates strongly with the orbital 2p(H) in the formation of the conduction band. The analysis of elastic properties, calculated for the first time, by means of correlations with their equivalents calculated in CaH2, has placed the existence of two series of constants in a prominent position. The first one regroups the constants C-11, C-12 and C-33; the second one is formed by the other constants, including the bulk modulus B-0. This separation is confirmed by the analysis of charge densities. (C) 2000 Elsevier Science B.V. All rights reserved.