Properties of the phosphorus oxide radical, PO, its cation and anion in their ground electronic states: comparison of theoretical and experimental data

Experimental and theoretical data for the phosphorus oxide radical (PO), its cation (PO⁺) and anion (PO⁻) in their electronic ground states are reviewed. The internuclear distances, fundamental vibrational frequencies, bond orders, partial atomic charges, free valences, dipole moments, dissociation energies, ionization potential and electron affinity are discussed. The literature data are augmented by the results of a theoretical study including computations using restricted Hartree-Fock closed- and open-shell, generalized valence bond-perfect pairing, Møller-Plesset perturbation theory, complete active space self-consistent field, coupled-cluster with single and double substitutions up to the level augmented by a perturbative estimate of triple excitations and density functional theory methods.