ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Correlations in ionic solids by means of ab initio quantum chemistry

K. Doll, M. Dolg, P. Fulde, and H. Stoll

Max-Planck-Institut für Physik Komplexer Systeme, D-01187 Dresden, Germany

Abstract: Ab initio quantum-chemical methods are not necessarily restricted to molecules and have already been applied to calculate cohesive properties of semiconductors. We extended this method to ionic solids (MgO, CaO, NiO) and calculated cohesive energies and lattice constants. We obtain approximate to 80 % of the correlation contribution to the cohesive energy. Contributions due to the formation of ions are of the same order of magnitude for the cohesive energy as van der Waals-like interactions between the ions. Including correlations, the calculated lattice constants deviate by less than 1 % from the experimental values. Two main effects arising from correlations are found: the van der Waals-Like interaction between the ions reduces the lattice constant whereas intra-atomic correlation of the oxygen ion enforces a larger lattice constant due to the lower level spacing and therefore increasing importance of correlations at a larger lattice constant.

Chemical Papers 51 (6A) 357–362 (1997)