Liyana-Arachchi Thilanga P, Jamadagni Sumanth N, Eike David, Koenig Peter H, Siepmann J Ilja
Department of Chemistry and Chemical Theory Center, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA.
Computational Chemistry, Modeling and Simulation, The Procter & Gamble Company, 8611 Beckett Road, West Chester, Ohio 45069, USA.
J Chem Phys. 2015 Jan 28;142(4):044902. doi: 10.1063/1.4905918.
Three developments are presented that significantly expand the applicability of dissipative particle dynamics (DPD) simulations for symmetric and non-symmetric mixtures, where the former contain particles with equal repulsive parameter for self-interactions but a different repulsive parameter for cross-interactions, and the latter contain particles with different repulsive parameters also for the self-interactions. Monte Carlo and molecular dynamics simulations for unary phases covering a wide range of repulsive parameters and of densities for single-bead DPD particles point to deficiencies of the Groot and Warren equation of state (GW-EOS) [J. Chem. Phys. 107, 4423 (1997)]. A revised version, called rGW-EOS, is proposed here that is significantly more accurate over a wider range of parameters/densities. The second development is the generalization of the relationship between the Flory-Huggins χ parameter and the repulsive cross-interaction parameter when the two particles involved have different molecular volumes. The third aspect is an investigation of Gibbs ensemble Monte Carlo simulation protocols, which demonstrates the importance of volume fluctuations and excess volumes of mixing even for equimolar symmetric mixtures of DPD particles. As an illustrative example, the novel DPD methodology is applied to the prediction of the liquid-liquid equilibria for acetic anhydride/(n-hexane or n-octane) binary mixtures.
本文介绍了三项进展，这些进展显著扩展了耗散粒子动力学（DPD）模拟在对称和非对称混合物中的适用性。在对称混合物中，粒子的自相互作用具有相等的排斥参数，但交叉相互作用具有不同的排斥参数；在非对称混合物中，粒子的自相互作用也具有不同的排斥参数。针对单珠DPD粒子在广泛的排斥参数和密度范围内的一元相进行的蒙特卡罗和分子动力学模拟，指出了Groot和Warren状态方程（GW-EOS）[《化学物理杂志》107, 4423 (1997)]存在的不足。本文提出了一个修订版本，称为rGW-EOS，它在更广泛的参数/密度范围内具有显著更高的准确性。第二项进展是当涉及的两个粒子具有不同分子体积时，对Flory-Huggins χ参数与排斥交叉相互作用参数之间关系的推广。第三个方面是对吉布斯系综蒙特卡罗模拟协议的研究，该研究表明即使对于DPD粒子的等摩尔对称混合物，体积涨落和混合过量体积也很重要。作为一个示例，新的DPD方法被应用于预测乙酸酐/（正己烷或正辛烷）二元混合物的液-液平衡。
