Jagannathan Kamakshi, Yethiraj Arun
Department of Chemistry, University of Wisconsin, Madison, 53706, USA.
J Chem Phys. 2005 Jun 22;122(24):244506. doi: 10.1063/1.1940053.
Molecular-dynamics simulations are presented for the dynamic behavior of the Widom-Rowlinson mixture [B. Widom, and J. S. Rowlinson, J. Chem. Phys. 52, 1670 (1970)] at its critical point. This model consists of two components where like species do not interact and unlike species interact via a hard-core potential. Critical exponents are obtained from a finite-size scaling analysis. The self-diffusion coefficient shows no anomalous behavior near the critical point. The shear viscosity and thermal conductivity show no divergent behavior for the system sizes considered, although there is a significant critical enhancement. The mutual diffusion coefficient, D(AB), vanishes as D(AB) approximately xi(-1.26 +/- 0.08), where xi is the correlation length. This is different from the renormalization-group (D(AB) approximately xi(-1.065)) mode coupling theory (D(AB) approximately xi(-1)) predictions. The theories and simulations can be reconciled if we assume that logarithmic corrections to scaling are important.
本文给出了维杜姆 - 罗林森混合物[B. 维杜姆和J. S. 罗林森，《化学物理杂志》52, 1670 (1970)]在其临界点处动力学行为的分子动力学模拟。该模型由两个组分组成，同种分子间不相互作用，异种分子通过硬核势相互作用。临界指数通过有限尺寸标度分析获得。自扩散系数在临界点附近未表现出反常行为。在所考虑的系统尺寸下，剪切粘度和热导率未表现出发散行为，尽管存在显著的临界增强。互扩散系数D(AB) 随着D(AB) 近似为ξ^(-1.26 ± 0.08) 而消失，其中ξ是关联长度。这与重整化群（D(AB) 近似为ξ^(-1.065)）和模式耦合理论（D(AB) 近似为ξ^(-1)）的预测不同。如果我们假设对标度的对数修正很重要，则理论和模拟结果可以相互协调。
