Solvent effects on the ultrafast nonradiative deactivation mechanisms of thymine in aqueous solution: Excited-state QM/MM molecular dynamics simulations

摘要: On-the-fly excited-state quantum mechanics/molecular mechanics molecular dynamics (QM/MM-MD) simulations of thymine in aqueous solution are performed to investigate the role solvent water molecules on nonradiative deactivation process. The complete active space second-order perturbation theory (CASPT2) method is employed for a molecule as QM part order provide reliable description potential energies. It found that, addition previously reported pathway involving twisting C-C double bond pyrimidine ring, another efficient leading conical intersections that accompanies out-of-plane displacement carbonyl group observed solution. Decay through this not gas phase simulations, and our analysis indicates hydrogen bonds with play key stabilizing energies additional decay pathway.