Theory of small-polaron band conduction in ultrapure organic crystals
  We present a novel theory of charge-carrier mobilities in organic molecular crystals of high purity. Our approach is based on Holstein's original concept of small-polaron bands but generalized with respect to the inclusion of nonlocal electron-phonon coupling. We derive an explicit expression for the mobilities as a function of temperature and, using ab-initio methods to obtain the material parameters, we demonstrate its predictive power by applying it to naphthalene. The results show a remarkably good agreement with experiments and provide new insight into the difference between electron and hole mobilities as well as their peculiar algebraic and anisotropic temperature dependences. 
K. Hannewald and P.A. Bobbert