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.