A semiempirical potential for alkali halide diatoms with damped interactions I. Rittner potential.

A new semiempirical potential is described for the ground state X 1 Σ + of the alkali halide diatoms. The model potential is the first to account for the damping of all the electrostatic and induction potential terms as well as of the long-range dispersion potential. Accordingly, the potential does not have a negative singularity at vanishingly small internuclear distances and is the first Rittner-type model with a realistic dependence of the repulsion at short distances. The new potential is tested by comparing with ab initio potentials, which presently are only available in the well region for the molecules LiF, LiCl and CsI. The three parameters of the new potential are determined by fitting the latest experimental parameters for the well depth D e , bond distance R e and vibrational frequency ω e . The new potential is in good agreement with the ab initio potentials.