A molecular symmetry analysis of the electronic states and transition dipole moments for molecules with two torsional degrees of freedom

Abstract

We present a molecular symmetry analysis of electronic states and transition dipole moments for molecules which undergo large amplitude intramolecular torsions. The method is based on the correlation between the point group of the molecule at highly symmetric configurations and the molecularsymmetrygroup.Asanexample,wedeterminetheglobalirreduciblerepresentationsofthe electronic states and transition dipole moments for the quinodimethane derivative 2-[4-(cyclopenta2,4-dien-1-ylidene)cyclohexa-2,5-dien-1-ylidene]-2H-1,3-dioxole for which two torsional degrees of freedom can be activated upon photo-excitation and construct the resulting symmetry adapted transition dipole functions.