Quantifying the Lifetime of Triplet Energy Transfer Processes in Organic Chromophores: A Case Study of 4-(2-Naphthylmethyl)benzaldehyde.

We simulate the dynamics of triplet-triplet energy transfer in a donor-bridge-acceptor system [4-(2-naphthylmethyl)benzaldehyde] with surface hopping, using electronic energies, gradients, and derivative couplings that are calculated on the fly. Using Boys localization to diabatize electronic states, we calculate energy transfer rates that agree favorably with experiment. The atomistic nature of our dynamical investigation produces several unique insights into this energy transfer reaction including an approximation of the decoherence time for the energy transfer process and the observation that the reaction pathway passes through a conical intersection.