THEORETICAL POTENTIAL-ENERGY FUNCTIONS AND SPECTROSCOPIC DATA FOR THE PH2+ ION

Three-dimensional potential-energy functions for the (X) over tilde(1)A(1) and (A) over tilde(1)B(1) states of PH2+ have been derived from extensive ab initio multi-reference configuration interaction (MRCI) calculations. Spectroscopic constants and quartic force fields have been derived from the potential-energy functions by second-order perturbation theory. These data are believed to be reasonable predictions for this molecular ion for which there is little experimental data. Rovibrational levels have been calculated by a variational method up to 10 000 cm(-1) for the ground state and up to 8000 cm(-1) for the excited state. Coriolis coupling and Fermi and Darling-Dennison resonances have been investigated in detail.