Quantum molecular dynamics simulations of the effect of secondary modes on the photoisomerization of a retinal chromophore model

In this paper, we report on the performance of various quantum molecu- lar dynamics simulation methods in describing the photo-induced nonadi- abatic dynamics underlying the isomerization process of the retinal chromophore in rhodopsin. We focus on purely quantum vibronic wavepacket techniques and on various trajectory-based schemes, discussing their capability of accurately capture the isomerization process using a two-dimensional two-state model system coupled to an environment of secondary harmonic modes. Numerical results of various algorithms and time-independent grid schemes for the purely quantum approaches are presented, which also serve as benchmark for the trajectory-based calculations. Independent-trajectory and coupled-trajectory methods are compared as well, devoting particular attention to the scaling of their computational cost when increasing the number of degrees of freedom.