Singlet excitons in crystalline naphthalene,antracene, tetracene and pentacene

The energies and oscillator strengths of exciton transitions in crystalline naphthalene, anthracene, tetracene and pentacene are calculated using second quantized boson theory. The lattice sums of Coulomb exciton transfer interactions consist of an Ewald sum of molecular point dipole-dipole interations and a direct sum of nondipolar interactions calculated from PPP wavefunctions using the atomic—multipole representation of transition charge densities. The calculated exciton energies and oscillator strengths are compared with available experimental data. For anthracene, inclusion of the nondipolar interactions leads to substantially better agreement between theory and experiment. For tetracene and pentracene, the factor group splittings of the lowest transition are determined primarily by crystal induced mixing with higher transitions.