Theory of bandwidth narrowing in oligo-acene crystals

We present a novel theoretical description of polaron bandwidth narrowing in organic molecular crystals. Based on a solution of a mixed Holstein-Peierls model, we derive an explicit expression for the bandwidths as a function of temperature. This formula generalizes the result of the Holstein model by treating local and nonlocal electron-phonon coupling on equal footing. The subsequent application to model studies for oligo-acene crystals provides new microscopic insight into the relevance of the different coupling mechanisms and explains various experimental findings