REORGANIZATION ENERGIES IN BENZENE, NAPHTHALENE, AND ANTHRACENE

The electronic structure and geometry are calculated for benzene, naphthalene and anthracene and their negative ions using ab initio methods with good basis sets and with correlation included at the MP2 level. The internal reorganization energy for adding an electron to the neutral molecule (lambda(1)) and for removing an electron from the negative ion (lambda(2)) are found to be nearly the same. The calculations suggest that lambda(1) and lambda(2) for anthracene are about half of the corresponding values for benzene. Reorganization energies are considerably reduced when correlation effects are included. At the MP2 level a good geometry of the neutral molecule is obtained only if the basis set contains polarization functions, whereas lambda(1) and lambda(2) are quite independent of extensions of 6-31G. Predictions of reorganization energies based on Huckel bond orders are found to be excellent.