Quantum dynamics from classical mechanics on coupled potentials

We discuss optical transitions between two potential energy surfaces of quantum systems driven by ultrafast laser pulses using the final value representation of the coherent state propagator (FINCO). Based on a rigorous derivation from the time dependent Schrödinger equation (TDSE), this approach relies on Bohmian-like but complex-valued classical trajectories. Trajectories associated with each potential surface evolve in their own manifolds according to Newton’s laws with complex coordinates and momenta. Population transfer between the surfaces is taken into account naturally via self consistent equations of motion without any need for surface hopping. This non-stochastic method enables accurate calculation of wavefunction amplitudes, not just probabilities.

In this study we consider systems exhibiting optical excitations and subsequent nuclear dynamics induced via shaped laser pulses with arbitrary phase and amplitude similar to the experimental work reported by Scherer, et. al, J. Chem. Phys. 96 4180 (1992). The reconstructed wavepackets are compared with quantum results obtained via the split operator method.