Electronic Couplings for Photoinduced Electron Transfer and Excitation Energy Transfer Computed Using Excited States of Noninteracting Molecules

A new computational scheme to calculate electronic coupling for photoinduced electron transfer and excitation energy transfer is described. The transfer integral between predefined quasi-diabatic states is expressed through adiabatic excitation energies of the system and expansion coefficients derived by decomposition of the transition density matrix of the reference states. To demonstrate the feasibility of the developed approach, electronic couplings for charge separation and exciton transfer in a heterojunction composed of quaterthiophene and C 60 fullerene are computed at the DFT/ω-B97XD level.