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 confi guration interaction (CI) spaces is proposed. Localization of molecula r orbitals is implemented on the basis of interaction frontier orbital s. A small number of configuration state functions responsible for the transition, specified by the localization, are set up to generate a C I space for calculation of the transition moments aiming at eventual a pplications to large molecules such as peptides. This method is applie d to propene, 2-methylpropenal and N-methylacetamide as model systems for a critical assessment of the reliability and efficiency. (C) 1998 Elsevier Science B.V. All rights reserved.