Abstract
A projected valence bond method is used to obtain adiabatic and diabatic states for the study of the H++Cs collisional system. By freezing an adjusted Hartree Fock type Cs+ core the electronic problem is reduced to that of treating the outer electron of the (H-Cs)+ quasimolecule. The present treatment is designed to correct some serious defects of previous theoretical approaches. The calculated well in the adiabatic potential energy curve correlated with H++Cs satisfactorily accounts for the rainbow structures observed recently by Scheidt and colleagues (1977, 1978) in the measured elastic differential cross sections at low energy.