A method for calculating electric dipole transition moments using small configuration interaction spaces based on the concept of interaction frontier orbitals

A method for calculation of the transition moments using minimal configuration interaction (CI) spaces is proposed. Localization of molecular orbitals is implemented on the basis of interaction frontier orbitals. A small number of configuration state functions responsible for the transition, specified by the localization, are set up to generate a CI space for calculation of the transition moments aiming at eventual applications to large molecules such as peptides. This method is applied to propene, 2-methylpropenal and N-methylacetamide as model systems for a critical assessment of the reliability and efficiency.