Computing the Kirkwood g-Factor by Combining Constant Maxwell Electric Field and Electric Displacement Simulations: Application to the Dielectric Constant of Liquid Water.
Computing the Kirkwood g-Factor by Combining Constant Maxwell Electric Field and Electric Displacement Simulations: Application to the Dielectric Constant of Liquid Water.
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DOI：
10.1021/acs.jpclett.6b01127
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发表时间：
2016-07
期刊：
影响因子：
--
通讯作者：
Chao Zhang;J. Hutter;M. Sprik
中科院分区：
文献类型：
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作者：
Chao Zhang;J. Hutter;M. Sprik
在他1939年的经典论文中，柯克伍德将极性液体的宏观介电常数与通过g因子（后来以他的名字命名）测量的局部取向顺序联系起来，并提出在短距离处的相应介电常数实际上等于“分子量级的距离”之后的宏观值[柯克伍德，J. Chem. Phys.，1939，7，911 ]。在这里，我们展示了一种简单的方法，通过叠加恒定电场E和恒定电位移D模拟的结果，从分子动力学（MD）模拟中提取短程柯克伍德g因子[ Zhang和Sprik，B：Condens.物质材料。物理、2016，93，144201 ]。介电常数现在可以从短距离的偶极子波动中估计，而不是从整个MD单元的偶极矩的缓慢波动中估计，从而加速收敛。利用这一特点，我们计算的体积介电常数的液体水建模的广义梯度近似（PBE）密度泛函理论，并发现它至少比实验值大40%。
In his classic 1939 paper, Kirkwood linked the macroscopic dielectric constant of polar liquids to the local orientational order as measured by the g-factor (later named after him) and suggested that the corresponding dielectric constant at short-range is effectively equal to the macroscopic value just after "a distance of molecular magnitude" [ Kirkwood, J. Chem. Phys., 1939, 7, 911 ]. Here, we show a simple approach to extract the short-ranged Kirkwood g-factor from molecular dynamics (MD) simulation by superposing the outcomes of constant electric field E and constant electric displacement D simulations [ Zhang and Sprik, Phys. Rev. B: Condens. Matter Mater. Phys., 2016, 93, 144201 ]. Rather than from the notoriously slow fluctuations of the dipole moment of the full MD cell, the dielectric constant can now be estimated from dipole fluctuations at short-range, accelerating the convergence. Exploiting this feature, we computed the bulk dielectric constant of liquid water modeled in the generalized gradient approximation (PBE) to density functional theory and found it to be at least 40% larger than the experimental value.