The potential energy coefficients for internal rotation in CH2DSH and CHD2SH

An internal axis method (IAM) has been used to determine the potential ener gy coefficients V-1, V-2, and V-3 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(sigma), 3(e(2))-2(o(2)), determines the torsional state assignment for th is Q-branch series as o(2) to e(2) that was not known previously. For CH2DS H, the potential energy coefficients are V-1 = 4.54 cm(-1) V-2 -9.36 cm(-1) , V-3 = 440.50 cm(-1): for CHD2SH, V-2 = -4.12 cm(-1), V-2 8.23 cm(-1), V-3 = 439.65 cm(-1). Nonrigidity coefficients have also been determined for bo th the trans and pauche conformations of the ground state. (C) 2001 Academi c Press.