Variational random phase approximation using the one-component-plasma reference

Abstract

Abstract We propose a simplified variational random phase approximation (VRPA) for the structure factor of liquid alkali metals using the one-component-plasma (OCP) reference. Our formulation combines the standard random phase approximation (RPA) for the structure factor with the variational form of the mean spherical approximation (MSA) for the reference system. Our formula is similar to the optimized random phase approximation (ORPA), but can avoid the introduction of the fictitious hard core to the reference system. Application of the method to liquid Na and K indicates that the accuracy of this method is comparable with the ORPA using the hard sphere reference.