Solvent and field effects on photoinduced ring opening: dynamics of furan as a case study

In this work, we approach the simulation of the light-induced ultrafast dynamics of furan from a new angle. We deeply investigate the impact of the explicit inclusion of the incident pulse and the description of protic and aprotic solvents on the photorelaxation. Upon excitation, furan is driven back to its electronic ground state via two deactivation channels: one characterized by ring-puckering of the oxygen and one by ring opening via breaking of the carbon-oxygen bond. We found that explicitly including an 11 fs pulse in the simulation has a slight accelerating effect on the population dynamics; in addition, we could see an increase in the coherent motion of the puckering mode of furan. Interestingly, both solvents facilitate the ring opening, but it is more enhanced in protic methanol due to hydrogen-bonding of the solvent stabilizing the ring-open molecule. Overall, the study validates the general robustness of the routine approximation of simulating photodynamics in the gas phase using the sudden excitation approximation, but it also highlights differences that form the basis for future improvements of extending nonadiabatic dynamics simulations to an improved description of solvent and field effects.