Electronic polarization effects on charge carriers in anthracene: A valence bond study

A semiempirical quantum-chemical model based on a fragment orbital formalism is presented to assess molecular parameters relevant to charge transport in organic crystals. The mixed valence bond/Hartree-Fock approach provides an efficient integrated framework to evaluate the electronic polarization effects induced by localized charge carriers and the associated impact on the matrix elements mediating electron migration in the hopping regime. This formalism, applied here to anthracene clusters of increasing sizes and dimensionalities, yields the electrostatic and polarization contributions to the total interaction energy of the neutral and charged aggregates and leads to a reduction in the effective bandwidth by similar to 10%-20% as a result of the polarization cloud.