Validity of describing reaction coordinate of intramolecular charge transfer of 1,3-dinitrobenzene anion radical using constrained density functional theory

In this work, we explore the validity of the application of the constrained density functional theory (CDFT) to the study of intramolecular charge transfer reactions. Accordingly, we carry out single-point calculation using CDFT and MRMP2 at each point in the intramolecular charge-transfer reaction coordinate of 1,3-dinitrobenzene anion radical, calculated using the complete active space self-consistent filed theory (CASSCF). We show that the CDFT//CASSCF and MRMP2//CASSCF energy profiles are qualitatively and quantitatively similar. Therefore, we conclude that CDFT is a good tool for studying the intramolecular charge-transfer reactions.