London potential‐energy surfaces for symmetrical alkali trimers

Abstract

AbstractSemiempirical valence bond calculations have been performed on the symmetrical alkali trimers in order to obtain their potential‐energy surface, binding energy, and equilibrium geometry. For these calculations original and generalized Rosen–Morse potentials for the ground state and two similar types of new potentials for the triplet state of alkali dimers have been used. At small internuclear distances the potential surfaces show a shallow well which extends into the entrance and exit valleys without an energy barrier. The trimers are found to be stable both in linear and bent configurations, but the most stable configuration in each case is linear and symmetric. The force constants corresponding to stretching and bending deformations of the trimers have been calculated for this configuration. It has been observed that unlike the stretching, the bending deformation does not sensitively affect the energy variation of the ground state of the trimers.