Density-functional Lcao Calculations of Periodic-systems - Effect of An A-posteriori Correction of the Hartree-fock Energy On the Physical-properties of Ionic Sulfur-compounds

Density functional theory is taken into account to correct 'a posteriori' the total energy calculated with ab initio Hartree-Fock theory. Two models are adopted: the first one is the local density approximation parametrized by Ceperley and Alder while the second one is non-local and corresponds to the formulation proposed by Perdew. The changes in physical properties of ionic sulfide compounds (equilibrium geometry, formation energy, elastic constants, phase transition B-1 --> B-3 in MgS and surface relaxation) associated with the electronic correlation are evaluated.