Disentangling the Effects of Non-Adiabatic Interactions upon Ion Dynamics within Warm Dense Hydrogen

Warm dense matter (WDM) is a complex state that inhabits the region of parameter space connecting condensed matter to classical plasma physics. In this intermediate regime, we investigate the significance of non-adiabatic electron-ion interactions on ion dynamics. We directly compare diffusivity from the non-adiabatic electron force field (eFF) computational model to an adiabatic molecular dynamics (MD) simulation to disentangle electron-ion interactions. A tabulated potential developed through a force matching algorithm ensures the only difference between the models is due to the electronic motion. We implement this new method to characterize non-adiabatic effects on the diffusivity of warm dense hydrogen over a wide range of temperatures and densities and find that non-adiabatic effects may be more important for lower densities and temperatures. However, for thermodynamic conditions where experimental electron-ion equilibration data exists, we find non-adiabatic effects play little role, with only a 1.5% change due to non-adiabatic electron-ion interactions.