EFFECTIVE POTENTIALS FOR SPECTATOR GROUPS IN MOLECULAR-SYSTEMS - TRANSITION ENERGIES AND TRANSITION MOMENTS

It is shown that the method for the description of spectator groups in molecular systems by an effective potential as discussed by von Arnim can be employed easily in configuration interaction calculations. Not only energies but also the wavefunctions seem to be described satisfa ctorily. This is demonstrated by the good reproduction of the shift in the n-->pi transition of CH2O and the change in its rotary strengths due to H2O binding.