Inhomogeneous fluid of penetrable-spheres: application of the random phase approximation

Yan Xiang, Derek Frydel

Published 2017-04-22Version 1

The focus of the present work is the application of the random phase approximation (RPA), derived in Ref. [D. Frydel and M. Ma, Phys. Rev. E {\bf 93}, 062112 (2016)] for inhomogeneous fluids, to penetrable-spheres. As penetrable-spheres transform into hard-spheres with increasing interactions, they provide an interesting case for exploring the RPA, its shortcomings and limitations, the weak- versus the strong-coupling limit. Two scenarios taken up by the present study are a one-component and a two-component fluids with symmetric interactions. It is the latter case for which the RPA is particularly useful. In this case the mean-field contributions are cancelled and any contributions from particle interactions are accounted for by correlations. The accuracy of the RPA for this case is the result of a somewhat lucky cancellation of errors.