Ion-ion interaction and equation of state of a dense plasma: Application to beryllium

A recent model treating the structure of ‘‘simple plasmas’’ as that of high-temperature liquid metals is used here to calculate the equation of state of dense beryllium plasmas, for values of compression between 0.2 and 6, and temperatures up to 100 eV. This model gets rid of the standard simplified descriptions of ionic distributions (isolated ion sphere, uniform positive background, etc.); it applies when the electronic structure justifies the use of a binary pair interaction. This interaction is calculated, for every density and temperature, using the self-consistent electronic charge density obtained in a density-functional-theory calculation. The statistical mechanics of the ion fluid is treated via a modified hypernetted-chain integral equation. The various contributions to the equation of state are presented and discussed, and comparisons with other theories are made.