A simple method for determining the ionic structure of warm dense matter

A model for dense homo-nuclear plasmas that couples an average atom model for the calculation of the electronic structure to the quantum Ornstein–Zernike equations describing the ionic structure is summarized and described pedagogically. The model is applied to the calculation of ion–ion pair distribution functions gII(r) for tungsten in the warm and hot dense matter regimes. These results are compared to orbital-free molecular dynamics simulations and excellent agreement is found. Calculations of gII(r) with a simple version of the model (which we call the ion-sphere model) are in remarkable agreement with those of the full model. This ion-sphere model provides a simple and efficient method of calculating accurate gII(r) for warm and hot dense matter for many applications involving low- to high-Z elements with a modest investment of effort.