Computations have been tperformed for the singlet and triplet electronic states of varying orientations of naphthalene dimer. The dependence of excition splitting upon orientation and intermonomer sdistance was explored. Splittingsd of triplet states are seen to be nontrivial at typical bonding distances, commensurate with the splittings of weakly allowed singlet states. Charge-transfer interaction with the excimer states is seen to the most significant in face-to-face orientations whihc can allow closer approach of the two moomers. Predictions of the prominent features of the singlet-singlet ad triplet-triplet absorption spectra agree well with experimental findings. A spin-orbit channel-counting scheme is introduced to account for observed radiative and nonradiative decay of the T-1 triplet state of the monomer, and then applied to the dimer. The mechanism has been found for the observed more rapid phosphoresene of the T_1 state of the dimer when placed in orientations lacking inversion symmetry
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