Electron-phonon coupling in naphthalene crystal

We investigate the electron interactions with optical phonons in crystalline naphthalene. The lattice phonon modes were computed at both DFT and empirical force field levels. The electron-phonon couplings were evaluated by means of numerical differentiation; in this approach, the crystal geometry is distorted along normal modes and transfer integrals for several selected molecular pairs are then computed at each distorted geometry. We find that the DFT and force field results for phonon frequencies and electron-phonon couplings compare very well. Interestingly, several phonon modes are calculated to display significant quadratic electron-phonon coupling. In addition, we have also performed electronic band-structure calculations and derived the effective masses for both electrons and holes.