AB-INITIO STUDY OF THE LIH+ MOLECULE, ELECTRONIC INTERACTION ANALYSIS AND LIH UV PHOTOELECTRON-SPECTRUM

All adiabatic curves of LiH+ dissociating into Li(2s, 2p, 3s, 3p, 3d) + H+ and Li+ + H(1s, 2s, 2p) are determined by an ab initio approach involving a non-empirical pseudopotential for the Li(1s(2)) core and core valence correlation corrections. The resulting spectroscopic constants and vibrational level spacings of all these states are presented. From the usual semiclassical approximations an analysis of the high energy vibrational level spacing is performed allowing for accurate long range extrapolations. For the lowest curves dissociating into Li+ + H(1s) and Li(2s) + H+ an analysis of the main electronic interactions is carried out from a diabatic model and reveals the importance of the binding charge delocalisation effects versus the polarisation (charge localised) ones. In addition the UH photoelectron spectrum is calculated. An interesting feature of that spectrum is that both bound-bound and bound-free transitions coexist due to the particular shape of the LiH and LiH+ potential energy curves.