Abstract
A finite LiH lattice whose Madelung potential in the central region closely approximates the Madelung potential in the host crystal is constructed. Hartree-Fock calculations were then carried out on lithium hydride clusters both within the crystal and as isolated species. The many body expansion terms and the probability of ionic motions which result in diffusion are examined and relaxation around diffused ions is taken into account. Calculations confirm that the many body expansion terms in the crystal environment are both convergent and smaller than for the isolated clusters. The two-ion rotation mechanism is the most probable. The barrier height for cation diffusion is less than for anion diffusion suggesting easier transfer of cations rather than anions within the LiH crystal. The results are correlated with those reported previously on LiF crystal.