Ab initiocalculations on low-lying electronic states of the PX, PX⁺and PX⁻species (X= H, F and Cl)

Ab initio investigations with a split-valence plus diffuse and polarization functions basis sets extended by Møller-Plesset perturbation theory up to fourth-order (including single, double, triple and quadruple excitations) on lower-lying bound electronic states of three diatomic phosphinidenes PH, PF and PCl and their cations and anions are reported. Except for the electron affinities which are underestimated, calculated spectroscopic parameters can favourably be compared with experimental data. They confirm previous assignments for a number of band systems and contribute to clarify some ambiguous situations. Of particular interest, it is shown that the MP2 level (with appropriate basis set) may provide useful energetic data for larger phosphinidenes species.