Inclusion of Energy Loss in Models of Laser Irradiated Gold Films via Classical Molecular Dynamics.

The structural evolution of laser-excited systems of gold has previously been measured through ultrafast MeV electron diffraction. However, there has been a long-standing inability of atomistic simulations to provide a consistent picture of the melt process, concluding in large discrepancies between the predicted threshold energy density for complete melt, as well as the the transition between heterogeneous and homogeneous melting. We employ two-temperature classical molecular dynamics simulations utilizing a highly optimized embedded-atom-method potential. We are able to match time-resolved electron diffraction data, and find consistency between atomistic simulations and experiments, by allowing laser energy to be transported away from the interaction region. This additional energy-loss pathway, which scales strongly with laser fluence, we attribute to fast electron production in the target.