Singh Jayant K, Errington Jeffrey R
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. 2006 Jan 26;110(3):1369-76. doi: 10.1021/jp055170i.
Grand-canonical transition-matrix Monte Carlo is combined with configurational-bias and expanded ensemble Monte Carlo techniques to obtain saturated densities and vapor pressures of select n-alkanes. Surface tension values for butane, hexane, and octane are also computed via the finite-size scaling method of Binder. The exponential-6 model of Errington and Panagiotopoulos is used to describe the molecular interactions. The effect of the number of configurational-bias trial conformations on the efficiency of phase equilibra calculations is studied. We find that a broad range of trial conformation numbers give reasonable performance, with the optimal value increasing with decreasing temperature for a fixed chain length. Phase coexistence properties are in good agreement with literature values and are obtained with very reasonable computing resources. Similar to other recently developed n-alkane force fields, the exponential-6 model overestimates the surface tension relative to experimental values. Statistical uncertainties for coexistence properties obtained with the current approach are relatively small compared to existing methods.
巨正则转移矩阵蒙特卡罗方法与构型偏置和扩展系综蒙特卡罗技术相结合，以获得选定正构烷烃的饱和密度和蒸气压。丁烷、己烷和辛烷的表面张力值也通过Binder的有限尺寸标度法计算得出。采用Errington和Panagiotopoulos的指数-6模型来描述分子间相互作用。研究了构型偏置试验构象数对相平衡计算效率的影响。我们发现，广泛的试验构象数能给出合理的性能，对于固定链长，最佳值随温度降低而增加。相共存性质与文献值吻合良好，且所需计算资源非常合理。与其他最近开发的正构烷烃力场类似，指数-6模型相对于实验值高估了表面张力。与现有方法相比，用当前方法获得的共存性质的统计不确定性相对较小。
