QM/MM surface-hopping dynamics of a bridged azobenzene derivative.

Ethylene-bridged azobenzene (diazocine) has been shown to have superior photochemical properties. So far, however, experimental and theoretical quantum yields did not match, not even qualitatively. Here, a large-scale QM/MM surface-hopping study of this molecule is presented. For both photo-isomerization directions, surprisingly prominent solvent effects are found and analyzed by detailed comparisons against gas phase dynamics and experimental data. By taking explicit n-hexane solvent into account, the quantum yields change markedly and approach the experimental values, where the same solvent was used.