维杜姆-罗林森混合物的临界行为：共存直径与序参量。

Critical behavior of the Widom-Rowlinson mixture: coexistence diameter and order parameter.

作者信息

Vink R L C

机构信息

Institut für Theoretische Physik II, Heinrich Heine Universität Düsseldorf, Universitätsstrasse 1, 40225 Düsseldorf, Germany.

出版信息

J Chem Phys. 2006 Mar 7;124(9):94502. doi: 10.1063/1.2171191.

DOI:10.1063/1.2171191

PMID:16526862

Abstract

The critical behavior of the Widom-Rowlinson [J. Chem. Phys. 52, 1670 (1970)] is studied in d = 3 dimensions by means of grand canonical Monte Carlo simulations. The finite-size scaling approach of Kim et al. [Phys. Rev. Lett. 91, 065701 (2003)] is used to extract the order parameter and the coexistence diameter. It is demonstrated that the critical behavior of the diameter is dominated by a singular term proportional to t(1-alpha), with t the relative distance from the critical point, and alpha the critical exponent of the specific heat. No sign of a term proportional to t(2beta) could be detected, with beta the critical exponent of the order parameter, indicating that pressure mixing in this model is small. The critical density is measured to be rhosigma3 = 0.7486 +/- 0.0002, with sigma the particle diameter. The critical exponents alpha and beta, as well as the correlation length exponent nu, are also measured and shown to comply with d = 3 Ising criticality.

摘要

通过巨正则蒙特卡罗模拟研究了三维空间中维杜姆 - 罗林森体系[《化学物理杂志》52, 1670 (1970)]的临界行为。采用了金等人[《物理评论快报》91, 065701 (2003)]的有限尺寸标度方法来提取序参量和共存直径。结果表明，直径的临界行为由与(t^{(1 - \alpha)})成正比的奇异项主导，其中(t)是与临界点的相对距离，(\alpha)是比热临界指数。未检测到与(t^{(2\beta)})成正比的项的迹象，其中(\beta)是序参量临界指数，这表明该模型中的压力混合很小。测得临界密度为(\rho\sigma^3 = 0.7486 \pm 0.0002)，其中(\sigma)为粒子直径。还测量了临界指数(\alpha)和(\beta)以及关联长度指数(\nu)，结果表明它们符合三维伊辛临界性。