Computing a three-dimensional electronic energy manifold for the LiH + H <==> Li + H2 chemical reaction

We present a new three-dimensional potential energy surface (PES) for the electronic ground state of the LiH + H <==> Li + H2 reaction and further analyze specific aspects of the lower four excited electronic states. Our reactive PESs are calculated using a CASSCF method followed by an MRCI treatment of the correlation energy. The ground-state three-dimensional surface is then fitted by using our own version of the Aguado-Paniagua interpolation form [Aguado, A.; Paniagua, M. J. Chem. Phys. 1992, 96, 1265]. A review of the previous computational work on this system, to which we compare our present findings, is given in the introduction of the paper: with respect to such earlier calculations of the ground-state PES [Dunne, L. J.; Murrell, J. N.; Jemmer, P. Chem. Phys. Lett. 2001, 336, 1], our data confirm the absence of a barrier along the path to the LiH depletion reaction and further reveal possible spurious features of the earlier computed surface which may in turn affect the resulting rates from low-energy dynamic studies of the title system.