Simple accurate first-principles pair potentials for studying linear transport properties of Warm Dense Matter

Density functional theory asserts that all the thermodynamic and linear transport properties are a functional of the one-body electron density $n(r)$ of an electron-ion system. If we consider a warm-dense matter (WDM) system it usually consists of an electron system and an ion system in equilibrium at some temperature $T$. We may consider any single representative ion in the WDM together with its neutralizing electron density distribution $n(r)$ around it as well as the ion distribution $\rho(r)$. The latter is the crystal structure if the system is a solid. In a fluid $\rho(r)$ is spherically symmetric and simple. Such a neutral object is known as a neutral pseudoatom. The $n(r)$ can be reconstructed to give the free electron pile up $\Delta n_f(r)$ at the ion in a uniform electron gas of the appropriate density. We have proposed (since the 1980s) the construction of simple linear local (i.e., $s$-wave) electron-ion potentials $U_{ei}(q)$ as well as second-order ion-ion pair potentials $V_{ij}(q)$ derived from $\Delta n_f(q)$ as an appropriate and usually accurate method for obtaining thermodynamic and transport properties of WDMs. We illustrate this approach by applications to Al, Li, C and Silicon WDM fluids as well as mixtures. [1]PHYSICAL REVIEW E 94, 053211 (2016)