Time-resolved photoemission from a field-driven Holstein chain: A semi-classical Monte Carlo approach

We extend a recently developed time-dependent Monte Carlo method [1] which models the dynamics of electron and frozen phonon coupled systems to include the classical phonon motion. The numerical efficiency of the new method allows us to perform a self-consistent time evolution of the two coupled subsystems to time scales on the order of several picoseconds. We apply this novel method to study the dynamics of an excited state of a charge density wave (CDW) material in the context of pump-probe experiments. Our system is a half-filled, one-dimensional Holstein chain that exhibits CDW ordering due to Peierls transition. The chain is subjected to a time-dependent electromagnetic field that excites it out of equilibrium, and then the second pulse is used to probe its behavior. We capture the complete process of lattice excitation and subsequent relaxation to a new equilibrium, as manifested in the computed photoemission spectrum and relevant order parameters. Our method reveals an indirect driving mechanism of the lattice by the pump pulse. We separate two driving regimes, where the pump can either cause small perturbations or completely invert the initial CDW order.

[1] M. Weber, J. K. Freericks, arXiv:2108.05431 (2021).