VALENCE ELECTRONIC STATES OF NH2+ AND PH2+ DICATIONS

The ab initio second-order effective valence-shell Hamiltonian that is based on the multireference many-body perturbation theory has been ap plied to determine adiabatic potential energy curves for the valence S tates of NH2+ and PH2+ dications. For PH2+, three low-lying quasi-boun d states (X1SIGMA+, a3PI, A1PI) are found and their spectroscopic cons tants are characterized. In NH2+, no quasi-bound states are found. The potential energy curves for NH2+ are compared with those for PH2+ to understand the difference between these two valence isolectronic catio ns. (C) 1993 John Wiley & Sons, Inc.