DIRECT DETERMINATION OF SELF-CONSISTENT TOTAL ENERGIES AND CHARGE-DENSITIES OF SOLIDS - A STUDY OF THE COHESIVE PROPERTIES OF THE ALKALI-HALIDES

A recently proposed method for directly determining the self-consistent total energies and charge densities of solids is used to study the cohesive properties of all the alkali halides. The calculated lattice parameter, bulk modulus, and dissociation energy of each compound are reported and compared with the corresponding experimental data. The results have a good accuracy and their analysis gives some insights on possible improvements of the approximations that we have used. The relativistic contributions to the various properties have been evaluated by performing fully relativistic calculations for the heaviest compounds: The most relevant effect is an increase of the dissociation energies of the cesium halides which, for CsI, amounts to 7% of the experimental value.