Penetrable-Square-Well fluids: Analytical study and Monte Carlo simulations

摘要

We study structural and thermophysical properties of a one-dimensionalclassical fluid made of penetrable spheres interacting via an attractivesquare-well potential. Penetrability of the spheres is enforced by reducingfrom infinite to finite the repulsive energy barrier in the pair potentials Asa consequence, an exact analytical solution is lacking even in one dimension.Building upon previous exact analytical work in the low-density limit [Santos\textit{et al.}, Phys. Rev. E \text{77}, 051206 (2008)], we propose anapproximate theory valid at any density and in the low-penetrable regime. Bycomparison with specialized Monte Carlo simulations and integral equationtheories, we assess the regime of validity of the theory. We investigate thedegree of inconsistency among the various routes to thermodynamics and explorethe possibility of a fluid-fluid transition. Finally we locate the dependenceof the Fisher-Widom line on the degree of penetrability. Our results constitutethe first systematic study of penetrable spheres with attractions as aprototype model for soft systems.