The low-lying electronic states of PCl

The low-lying electronic states of PCl are investigated at a high level of correlation treatment using the CASSCF/MRSDCI approach, and the aug-cc-pVQZ-g basis set augmented with diffuse functions. The potential energy curves characterize unambiguously the complex structure of the electronic states, identifying avoided crossing regions among the 3Π states of relevance to experimentalists. Besides improving the accuracy of spectroscopic data upon previous theoretical studies, it unequivocally determines the dissociation energy of the ground state. The behavior of the dipole moment, transition dipole moment, and spin–orbit coupling constants with internuclear distance is also described. Relative intensities are predicted by the Einstein coefficients.