A THEORETICAL-STUDY OF THE STRUCTURE AND ENERGETICS OF STACKED DIMERSOF POLYCYCLIC AROMATIC-HYDROCARBONS - APPLICATION OF INDO 1 S METHOD TO SINGLET EXCIMERS OF NAPHTHALENE AND PHENANTHRENE/

We show here that, with the incorporation of intermolecular distance d ependence of pi-sigma interactions, the INDO 1/S method promises to be a very useful tool for investigating the structure and energetics of singlet excimers of polycyclic aromatic hydrocarbons. Application of t he method to naphthalene yields binding energies and vertical transiti on energies (in absorption and in emission) of the singlet excimer whi ch are in good agreement with experiment. The method also provides a p ossible explanation for the failure of phenanthrene to exhibit excimer fluorescence or the self-quenching of the monomer fluorescence.