Theoretical potential-energy functions and spectroscopic data for the PH2+ ion

Abstract

Three-dimensional potential-energy functions for the X ¹A₁ and ùB₁ states of PH₂⁺ have been derived from extensive ab initio multi-reference configuration interaction (MRCl) 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.