Electron-electron collisions in calculations of the electrical conductivity for warm dense matter based on density functional theory.

Density-functional-theory-based molecular dynamics simulations (DFT-MD) are a very successful tool to calculate the electrical conductivity of materials in the region of warm and dense matter. However, it requires a correction to implement the contribution of electron-electron collisions in the low-density, high-temperature region of plasmas. Based on the virial expansion of the electrical conductivity, a correction factor is presented, motivated by generalized linear response theory. To obtain accurate results for conductivity, the exact second virial coefficient is required, and a benchmark for high temperatures is given. For different materials, we identify the region in the temperature-density plane where the contribution of electron-electron collisions to the electrical conductivity is essential. We present new data of DFT-MD simulation of the electrical conductivity of Be for extreme conditions and show the validity of the virial expansion.