Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya (Barcelona Tech), B4-B5 Campus Nord, Barcelona, Catalonia 08034, Spain.
J Chem Phys. 2010 Jun 7;132(21):214505. doi: 10.1063/1.3429253.
The study of NaCl solutions in water at finite concentration, explicitly including polarization in water molecules and ions, has been carried out by molecular dynamics simulations. A comparison of the RPOL polarizable model with the rigid SPC/E potential for water has been included. Structure obtained with the two models does not show significant differences, although some deviations in the NaNa radial distribution functions at all concentrations are observed. Dielectric properties such as total and molecular dipole moment correlation functions revealed decay times of the order of 10 ps, roughly independent of concentration. The analysis of electric conductivity by means of current-current correlation functions also included the calculation of cross terms corresponding to dipole moment-current correlations, which proved to be non-neglectable at short times and especially relevant at high concentrations (m=4 mol kg(-1)). Frequency dependent dielectric constants and conductivities have been computed and the role of cross correlations has been analyzed. In all cases both concentration and cross correlations have significant influence in the results.
本研究采用分子动力学模拟方法，对有限浓度下的 NaCl 水溶液进行了研究，其中明确考虑了水分子和离子的极化作用。我们将 RPOL 极化模型与刚性 SPC/E 水势模型进行了比较。两种模型得到的结构没有显著差异，尽管在所有浓度下，NaNa 径向分布函数都存在一些偏差。介电性质，如总偶极矩相关函数和分子偶极矩相关函数，揭示了弛豫时间约为 10 ps，大致与浓度无关。通过电流-电流相关函数分析电导率时，还计算了对应于偶极矩-电流相关的交叉项，这些交叉项在短时间内不可忽略，尤其是在高浓度时（m=4 mol kg(-1)）尤为重要。我们还计算了频变介电常数和电导率，并分析了交叉相关的作用。在所有情况下，浓度和交叉相关都对结果有显著影响。
