Faculty of Science, J. E. Purkinje University, 400 96 Ústí nad Labem, Czech Republic.
J Chem Phys. 2013 Sep 28;139(12):124505. doi: 10.1063/1.4821153.
This paper deals with molecular simulation of the chemical potentials in aqueous electrolyte solutions for the water solvent and its relationship to chemical potential simulation results for the electrolyte solute. We use the Gibbs-Duhem equation linking the concentration dependence of these quantities to test the thermodynamic consistency of separate calculations of each quantity. We consider aqueous NaCl solutions at ambient conditions, using the standard SPC/E force field for water and the Joung-Cheatham force field for the electrolyte. We calculate the water chemical potential using the osmotic ensemble Monte Carlo algorithm by varying the number of water molecules at a constant amount of solute. We demonstrate numerical consistency of these results in terms of the Gibbs-Duhem equation in conjunction with our previous calculations of the electrolyte chemical potential. We present the chemical potential vs molality curves for both solvent and solute in the form of appropriately chosen analytical equations fitted to the simulation data. As a byproduct, in the context of the force fields considered, we also obtain values for the Henry convention standard molar chemical potential for aqueous NaCl using molality as the concentration variable and for the chemical potential of pure SPC/E water. These values are in reasonable agreement with the experimental values.
本文涉及水溶液中电解质化学势的分子模拟及其与电解质溶质化学势模拟结果的关系。我们使用吉布斯-杜恒方程将这些量的浓度依赖性联系起来，以检验每种量的单独计算的热力学一致性。我们考虑了环境条件下的 NaCl 水溶液，使用标准的 SPC/E 水分子力场和 Joung-Cheatham 电解质力场。我们通过在恒定数量的溶质中改变水分子的数量，使用渗透压系综蒙特卡罗算法来计算水的化学势。我们结合以前电解质化学势的计算，根据吉布斯-杜恒方程证明了这些结果的数值一致性。我们以适当选择的分析方程的形式呈现溶剂和溶质的化学势与物质的量的关系，这些方程拟合了模拟数据。作为副产品，在考虑的力场的背景下，我们还使用物质的量作为浓度变量，获得了亨利定律标准摩尔化学势对于水溶液中的 NaCl 和纯 SPC/E 水的数值。这些值与实验值吻合良好。
