Coupled electron-nuclear dynamics of molecular dissociation in few-cycle intense laser pulses by surface hopping method

We present theoretical study of the surface hopping method for simulation of coupled electron-nuclear dynamics of molecular dissociation in the presence of few-cycle intense laser pulses. We provide detailed analysis of the results from different versions of the surface hopping method for several systems. Furthermore, by benchmarking with exact numerical solutions of the coupled-channel time-dependent Schrodinger equation for those systems, we propose a simple modification to significantly improve the method and show that both dissociating nuclear wave packet and its phase can be quite accurately simulated. Our results also demonstrate the importance of decoherence and velocity adjustment during the hopping process. As phase of the wave packet becomes accessible, potential applications of the surface hopping method to other intense laser processes such as high-harmonic generation (HHG) with targets evolving in different potential energy surfaces can be envisioned. So far, only a limited number of applications to HHG have been reported, and more importantly, the adequacy of the simulation is still largely unknown.