RELAXATION AND ELECTRONIC-STRUCTURE OF SURFACES IN LITHIUM SULFIDE - A HARTREE-FOCK AB-INITIO APPROACH

Geometric relaxation and electronic structure of the (111) and (110) s urfaces of lithium sulphide were deduced from the study of slabs of di fferent thickness by a Hartree-Fock ab initio approach. An effective c ore pseudopotential basis set is used for the sulphur ion. The values of several physical constants of bulk Li2S obtained with this pseudopo tential and with an all-electron basis set justify its use for the stu dy of surfaces. Geometric structure, surface formation energy, band st ructure, density of states, electron charge density, atomic dipole and quadrupole moments were determined and analysed. The results are comp ared with those previously obtained for lithium oxide.