Configuration interaction and the theory of electronic factors in energy transfer and molecular exciton interactions

The theory established in J. Chem. Phys. 101, 10521 (1994), for electronic factors which promote interchromophore electronic energy transfer, exciton interactions and which provide the stabilization of excimers, is extended; first so as to include the possible contribution of doubly excited configurations. It is ascertained that there is a resultant effect upon the (interchromophore orbital overlap-dependent) through-configuration interaction, and a significant correction to the simple expression obtained previously for the Coulombic interaction. These CI effects are admitted to the general theory of the previous work and the cases of nonidentical, identical, and orthogonal donor and acceptor are discussed. Second, a description of superexchange effects is admitted to the theory. Two possible formalisms are developed and discussed.