Structure-thermodynamics relation of electrolyte solutions
Structure-thermodynamics relation of electrolyte solutions
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DOI：
10.1063/1.3097530
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发表时间：
2009-04-07
影响因子：
4.4
通讯作者：
Dzubiella, Joachim
中科院分区：
文献类型：
--
作者：
Kalcher, Immanuel;Dzubiella, Joachim
LiCl、NaCl、KCl、CsCl、KF和NaI水溶液的结构通过SPC/E水中经常使用的Dang力场的分子动力学（MD）模拟来计算。通过使用液态理论，我们整合的结构，以获得电解质的渗透系数φ和系统地研究力场质量和结构的后果，离子特定的本体热力学。渗透系数phi（chi）计算从精确的压缩性路线的阳离子-Cl-力场相匹配的实验浓度ρ小于或接近2 M，而碘化钠和KF参数失败。从维里途径（依赖于对势近似）比较phi（chi）和phi（v），表明多体效应对所有浓度大于或等于0.5M的盐都很重要。他们可以有效地纠正，但是，通过采用盐型和ρ依赖的介电常数ε（ρ），概括以前的意见，仅对NaCl。对于生理浓度，ρ小于或类似于0.5M，特定的渗透行为被发现是由短程阳离子-阴离子对电位只和后者的第二维里系数密切相关。所提出的方法和研究结果，基于简单的集成的电解质结构，使有效的MD力场细化直接基准的敏感的电解质热力学，而不是非集体，单离子属性。
The structure of aqueous LiCl, NaCl, KCl, CsCl, KF, and NaI solutions is calculated by molecular dynamics (MD) simulations of the frequently employed Dang force-field in SPC/E water. By using liquid state theory, we integrate the structure to obtain the electrolytes' osmotic coefficient phi and systematically investigate force-field quality and structural consequences to ion-specific bulk thermodynamics. The osmotic coefficients phi(chi) calculated from the exact compressibility route for the cation-Cl- force-fields match experiments for concentrations rho less than or similar to 2M, while NaI and KF parameters fail. Comparison of phi(chi) with phi(v) from the virial route, which relies on the pair potential approximation, shows that many-body effects become important for all salts above rho similar or equal to 0.5M. They can be efficiently corrected, however, by employing a salt-type and rho-dependent dielectric constant epsilon(rho), generalizing previous observations on NaCl only. For physiological concentrations, rho less than or similar to 0.5M, the specific osmotic behavior is found to be determined by the short-ranged cation-anion pair potential only and is strongly related to the second virial coefficient of the latter. Presented methods and findings, based on simple integrations over the electrolyte structure, enable efficient MD force-field refinement by direct benchmarking to the sensitive electrolyte thermodynamics, instead to noncollective, single ion properties.