Reduced matrix elements in semi-classical line shape calculations: Application to H2O-H2

Making reliable semi-classical calculations using the Modified Complex Robert and Bonamy formalism require an intermolecular potential expanded to a high order. Reduced matrix elements (RMEs) need to be computed for each component of the intermolecular potential using the wavefunctions of the states involved in the transition. Calculations for a number of transitions of 13 vibrational bands were performed using the vibrational dependent RMEs and using the ground state RMEs for both upper and lower states. The calculations show that for transitions that obey the sum rules the spectroscopic effect is small.