Yukawa Friedel-tail pair potentials for warm dense matter applications

Accurate equations of state (EOS) and plasma transport properties are essential for numerical simulations of warm dense matter, encountered in many high-energy-density experiments. Molecular dynamics (MD) is a simulation method that generates EOS and transport data using an externally provided potential to dynamically evolve the particles. To minimize computational cost, pair interaction potentials needed in MD may be obtained from the neutral-pseudoatom (NPA) approach, a form of single-ion density functional theory (DFT) where many-ion correlation effects are included. Standard N-ion DFT-MD also provides pair potentials by force matching but at much greater computational cost. In this talk we present a simple analytic model for pair potentials with physically meaningful parameters based on a Yukawa form with a thermally damped Friedel tail (YFT) applicable to systems containing free electrons. The YFT model accurately fits NPA pair potentials or the non-parametric potentials from N-ion DFT-MD force matching, showing excellent agreement for a wide range of conditions and recovers structural data like structure factors and pair-distribution functions; we discuss the applicability of the YFT model to ionic transport coefficients.