The Potential Energy Coefficients for Internal Rotation in CH2DSH and CHD2SH

An internal axis method (IAM) has been used to determine the potential energy coefficients V1, V2, and V3 to internal rotation in CH2DSH and CHD2SH. Two torsional differences for the gauche ground states and one torsional difference for the excited states were used to fix the V's. A fourth term, K(ς), 3(e2)–2(o2), determines the torsional state assignment for this Q-branch series as o2 to e2 that was not known previously. For CH2DSH, the potential energy coefficients are V1 = 4.54 cm−1, V2 = −9.36 cm−1, V3 = 440.50 cm−1; for CHD2SH, V1 = −4.12 cm−1, V2 = 8.23 cm−1, V3 = 439.65 cm−1. Nonrigidity coefficients have also been determined for both the trans and gauche conformations of the ground state.