Nonadiabatic ab initio molecular dynamics study of photoisomerization in N-salicilydenemethylfurylamine (SMFA).

The photoisomerization mechanisms of N-salicilydenemethylfurylamine upon excitation to the first singlet state are investigated by means of surface-hopping dynamics simulations based on the Zhu-Nakamura theory. Due to different orientations of the methyl-furyl part with respect to the salicylaldimine part and different orientations of hydroxy group with respect to the benzene ring, various stable structures are obtained in the optimization. The enol isomer, S0-ENOL-5a, is the most stable conformer. An ultrafast excited-state intramolecular proton transfer is observed after photoexcitation of the most stable enol conformer and then the molecule reaches the excited-state minimum. After the internal conversion around a conical intersection, the system relaxes to either the cis-keto or trans-keto region in the ground state. The potential energy profiles of the ground and the first excited singlet state are also calculated. According to full-dimensional nonadiabaticdynamics simulations and potential energy profiles, the trans-keto and cis-keto photoproducts can be responsible for the photochromic effect of N-salicilydenemethylfurylamine.