8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.69A modified soft-core fluid model for the direct correlationfunction of the square-shoulder and square-well fluidsIvan Guillen-Escamilla 11 Universidad de Guadalajara, Carr. Guadalajara-Ameca Km 45. 5, 46600, Ameca,MexicoWe propose a simple parametrization of the direct correlation function for the square-shoulder andsquare-well fluids. Our parametrization is based on an ansatz for the direct correlation func- tion ofa modified soft-core fluid, whose parameters are adjusted by fitting the data obtained from MonteCarlo simulations. Moreover, it is complemented with a Henderson-like parametriza- tion to reproducecorrectly the direct correlation inside the hard-core. We demonstrate that this parametrizationis in quantitaitve agreement with the numerical solution of the Ornstein-Zernike equation withinthe Perkus-Yevick approximation. We also show that our results are accurate in a large regimeof densities for different interaction ranges and potential strengths and therefore might be usefulfor introducing the square-shoulder and square-well fluids as new reference systems in elaboratetheoretical approximations.69