Vibronic calculations in benzene by CNDO/S

CNDO/S calculations of transition moments at displaced nuclear coordinates (Q) are performed for benzene. At every Q, the sum of the separately calculated Herzberg-Teller (H-T) components from the ground and the excited states is found to be equal to the computed total transition moment for each vibronically active normal mode in the 1B2u and 1B1u electronic transitions. The usually neglected ground state term is seen to be significantly weaker than the excited state component. The Q dependence of these transition moments is determined to be nearly linear, even to twice the root-mean-square displacement, although in some cases, higher order effects are found. The vibronic (H-T) CNDO/S oscillator strengths are presented.