Dissipation and effective interaction on the dynamic structure factor of warm dense matter

The relative impact of dissipation and the effective ionic interaction on the ionic dynamic structure factor is examined. Two disparate physically based models of dissipation, which can differ numerically by orders of magnitude, are used in molecular dynamics. We find a negligible impact on the amplitudes of the dynamic structure factors for physically realistic parameter values from both models. We then examine the effective ionic interaction by varying its strength, the size of the atomic core (through a pseudopotential) and the screening model. We find that ``diffusive" peaks in the dynamic structure factor are very sensitive to the form of the ionic interaction, and this sensitivity arises primarily from atomic physics through the pseudopotential. This suggests that it would be useful to employ the measured zero-frequency dynamic structure factor $S_{ii}(k,0)$ as a constraint on the effective interaction, which in turn can be used to compute physical properties.