The lowest triplet and singlet electronic states of the molecule SO

A comprehensive study of the singlet and triplet states of SO, correlating with the first two dissociation channels, is carried out using a state-aver aged complete active space self-consistent field/internally contracted mult ireference configuration-interaction approach, and correlation-consistent p olarized-valence quadruple-zeta basis sets. Potential energy curves and dip ole moment functions for all states are presented. Besides providing an acc urate and global description of the manifold of electronic states known to date, reliable evidence of two (1)Pi bound states, for which experimental e vidences were reported very recently, and a discussion of the vibrational n umbering problem of the transitions c(1)Sigma- --> a(1)Delta, and A'(3)Delt a --> X(3)Sigma(-) for which there has been some conflict in the available experimental data, are also presented. These results are of special relevan ce to elucidate further experimental assignments in the electronic spectros copy of SO. (C) 1999 Elsevier Science B.V. All rights reserved.