Comments on "State Equation for the Three-Dimensional System of 'Collapsing' Hard Spheres"

Abstract

andres@unex.esA recent paper [I. Klebanov et al. Mod. Phys. Lett. B 22 (2008) 3153; arXiv:0712.0433] claims that the exact solution of the Percus-Yevick (PY) integral equation for a system of hard spheres plus a step potential is obtained. The aim of this paper is to show that Klebanov et al.'s result is incompatible with the PY equation since it violates two known cases: the low-density limit and the hard-sphere limit.

Structure of the square-shoulder fluid

“…(2) This purely repulsive potential, apparently considered first by Hemmer and Stell 40 years ago [21], has been the subject of recent attention [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. On the one hand, it may lead to an isostructural solid-solid transition [22], to a fluid-solid coexisting line with a maximum melting temperature [23], to unusual phase behaviour [24][25][26] and to a rich variety of (self-organised) ordered structures [27][28][29][30].…”