Electronic states of SnS and SnS+: a configuration interaction study.

Ab initio based multireference configuration interaction calculations are carried out for SnS and its monopositive ion using effective core potentials. Potential energy curves and spectroscopic constants of the low-lying states of SnS and SnS+ are computed. The ground-state dissociation energies of the neutral and ionic species are about 4.71 and 2.86 eV, respectively which compare well with the available thermochemical data. The effect of d-electron correlation on the spectroscopic constants of a few low-lying states has been studied. The spin-orbit interaction has also been included to investigate its effect on the spectroscopic properties of both SnS and SnS+. Dipole moment and transition moment curves are also constructed as a function of the bond length. Transition probabilities of some dipole-allowed and spin-forbidden transitions are studied. Radiative lifetimes of a few low-lying states are estimated. The E1sigma+-X1sigma+ transition of SnS is predicted to be the strongest one. The components of the A2sigma(+)(1/2)-X2(2)pi(1/2) transition with parallel and perpendicular polarization are separately analyzed. The vertical ionization energies of the ground-state SnS to the ground and low-lying excited states of the monopositive ion are calculated.