Photodynamic behavior of electronic coupling in a N-methylformamide dimer.

The excited state dynamics of a N-methylformamide dimer in complex with water molecules has been studied using the complete active space self-consistent field (CASSCF) and CAS perturbation theory to the second order (CASPT2) methods. The extent of delocalization of the first two excited states resulting from (n → π*) transitions on both monomers was monitored during the time course of on-the-fly surface hopping nonadiabatic dynamics. The results suggest that the excited states prefer delocalization between the two monomers in the complex. The bridging water molecules increase the magnitude of electronic coupling via through-bond interactions.