Nonadiabatic molecular dynamics with solvent effects: A LR-TDDFT QM/MM study of ruthenium (II) tris (bipyridine) in water

The previously derived trajectory-based nonadiabatic molecular dynamics scheme [E. Tapavicza, I. Tavernelli, U. Rothlisberger, Phys. Rev. Lett. 98 (2007) 023001] is extended to include the coupling of the quantum system with a classically described environment. The dynamics is performed using LR-TDDFT energies and forces computed on-the-fly together with the nonadiabatic coupling vectors needed for the propagation of the nuclear coefficients according to Tully's fewest-switches surface hopping algorithm. The resulting LR-TDDFT-QM/MM approach is applied to the study of the ultrafast relaxation of the photoexcited singlet metal-to-ligand-charge-transfer state (¹MLCT) of [Ru(bpy)₃]²⁺ (bpy = 2,2′-bipyridine) in water. The observed intersystem crossing dynamics with the triplet MLCT is in good agreement with available experimental results.