Self-Consistent Incorporation of Generalized Born Model into RCI-LC-DFTB for Photoinduced Charge-Separated States.

Abstract

The self-consistent incorporation of Generalized Born (GB) model into the restriction-based configuration interaction long-range corrected density functional tight binding (RCI-LC-DFTB) framework enables a state-specific description of solvent polarization effects in photoinduced charge-separated (CS) states. In this scheme, the GB model contribution is constructed from the charge distribution of a selected target state and incorporated into the configuration interaction Hamiltonian through an effective one-electron operator, preserving the chemically intuitive interpretation of charge-localized diabatic configurations. We apply the method to two triphenylamine-naphthalene diimide (MTA-MNDI) donor-acceptor dyads connected by twisted phenylene-ethynylene bridges of different lengths. Our calculations demonstrate that solvent polarization significantly stabilizes the CS configuration, altering the energetic ordering between locally excited and CS states to thermodynamically drive charge separation. This approach offers a computationally efficient and chemically transparent framework for describing state-specific solvation and photophysical kinetics in large donor-acceptor assemblies.