A theoretical study of low-lying singlet electronic states of SF2

The four lowest-lying singlet electronic states of SF2 have been studied by using the CASSCF, CASPT2, and MRSDCI methods. The geometries of excited states were optimized by using the CASSCF and CASPT2 methods. The CASPT2 and MRSDCI adiabatic (T0) excitation energy calculations, using the CASPT2 geometries of the ground state and the excited states, predict that the X1A1, 11B1, 11A2, and 21B1 states are the four lowest-lying singlet states. The A and B states of SF2 are assigned to 11B1 and 21B1, respectively. However the B′ state, which was recently reported to lie between A and B, cannot be assigned.