Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260-4200, USA.
J Phys Chem B. 2010 Sep 9;114(35):11515-24. doi: 10.1021/jp103573k.
We examine a virial-like treatment for the equation of state of associating fluids defined in terms of a detailed molecular model. The approach implements Wertheim's formulation of statistical thermodynamics of a classical fluid of molecules having strong directionally dependent association interactions. We employ the theory in its fundamental form, which expresses the pressure as an expansion in two or more aggregation densities, which themselves are related to each other by other series expansions. We employ Mayer-sampling Monte Carlo simulations to evaluate the cluster integrals defining the coefficients appearing in these series, yielding a multidensity virial-like equation of state, appropriate for the molecular system for which the cluster integrals were computed. We demonstrate this approach with a well-studied Lennard-Jones + association model, considering cases of atoms having one and two binding sites, respectively, and including all clusters involving up to four atoms. It is shown for this application that the Wertheim treatment is vastly superior to the standard (single-density) virial formulation, which fails in its description of the associating-fluid equation of state at very low densities. The Wertheim formulation for associating fluids is seen to be effective up to densities where the standard virial treatment to the same order begins to fail when applied to nonassociating fluids.
我们研究了一种基于详细分子模型定义的缔合流体状态方程的类似维里的处理方法。该方法实现了 Wertheim 对具有强方向依赖性缔合相互作用的经典分子流体统计热力学的表述。我们采用了该理论的基本形式，该形式将压力表示为两个或更多聚集密度的展开式，而这些密度本身通过其他级数展开式相互关联。我们采用 Mayer-sampling Monte Carlo 模拟来评估定义这些级数中出现的系数的簇积分，从而得到适合计算簇积分的分子体系的多密度维里类似状态方程。我们用一个研究充分的 Lennard-Jones + 缔合模型来演示这种方法，分别考虑具有一个和两个结合位点的原子的情况，并包括涉及多达四个原子的所有簇。对于这种应用，表明 Wertheim 处理方法远远优于标准（单密度）维里公式，后者在非常低的密度下无法描述缔合流体状态方程。缔合流体的 Wertheim 公式在标准维里处理方法应用于非缔合流体时开始失效的密度范围内是有效的。
