Explicit Method To Evaluate the External Reorganization Energy of Charge-Transfer Reactions in Oligoacene Crystals Using the State-Specific Polarizable Force Field

The state-specific polarizable force field (SS-PFF) are parametrized for neutral and cationic oligoacenes based on QM calculations. The SS-PFF is applied to explicitly evaluate the electron–phonon interaction for localized hole–carrier charge transfer (CT) reactions in oligoacene crystals. A two-point model is proposed to estimate the total reorganization energy including internal and external contributions for hole–carrier CT reactions in oligoacene crystals. Orientation and separation dependent external reorganization energy are well described according to the potential energy surface of SS-PFF. Moreover, increasing the temperature leads to a small increase of the external reorganization energy of CT reactions.