State-specific solvation effect on the intramolecular charge transfer reaction in solution: A linear-response free energy TDDFT method

State-specific solvation for constructing excited-state free energy surfaces in solution is discussed within the framework of reference interaction site model/time-dependent density functional theory. The self-consistency between the solute electron density and solvation structure is achieved using the linear-response free energy approach. The proposed method is applied to the intramolecular charge-transfer (ICT) state formation of 4-(N-pyrrolo)benzonitrile. The linear-response solvation method underestimates the ICT state severely, and the calculation predicts erroneously that the reaction is endergonic. Therefore, it is essential to apply the state-specific method when the transition density fails in describing the solute–solvent interaction upon excitation.