A Initio Investigation of the Potential Surfaces of the Ground and Low-Lying Excited States of Carbon Disulfide

Potential energy surfaces for the ground singlet (S_0), lowest excited singlet (S _1), and lowest triplet (T _0) electronic states of carbon disulfide have been explored using ab initio Hartree-Fock (HF), Generalized Valence Bond (GVB) and Multiconfiguration Self-Consistent Field (MCSCF) computational methods in the 6-31G* basis. The lowest singlet hypersurface, S_0, contains the linear (D_{infty rm h}) equilibrium geometry ground state X^1Sigma_{rm g} ^+ and the previously unreported bent (C _{2rm v}) conformer ^1rm A_1. The calculated geometry of the linear state compares favorably with experiment; there are no experimental values to compare with the calculated geometry of the bent state. The transition state between the linear and bent conformers is determined to have C _{rm 2v}>=ometry and a barrier height of 7.7 kcal/mol. We also explore the ^1rm B_2 surface, S_1, and the ^3rm B_2 surface, T_0, finding the equilibrium geometry, dipole moments, and vibrational frequencies of these states as well as those of the ground state and bent conformer.