Zhou Shiqi
Research Institute of Modern Statistical Mechanics, Zhuzhou Institute of Technology, Wenhua Road, Zhuzhou city, 412008, P. R. China.
J Phys Chem B. 2005 Apr 21;109(15):7522-8. doi: 10.1021/jp0463619.
A recently proposed partitioned density functional (DF) approximation (Phys. Rev. E 2003, 68, 061201) and an adjustable parameter-free version of a Lagrangian theorem-based DF approximation (LTDFA: Phys. Lett. A 2003, 319, 279) are combined to propose a DF approximation for nonuniform Lennard-Jones (LJ) fluid. Predictions of the present DF approximation for local LJ solvent density inhomogeneity around a large LJ solute particle or hard core Yukawa particle are in good agreement with existing simulation data. An extensive investigation about the effect of solvent bath temperature, solvent-solute interaction range, solvent-solute interaction magnitude, and solute size on the local solvent density inhomogeneity is carried out with the present DF approximation. It is found that a plateau of solvent accumulation number as a function of solvent bath bulk density is due to a coupling between the solvent-solute interaction and solvent correlation whose mathematical expression is a convolution integral appearing in the density profile equation of the DF theory formalism. The coupling becomes stronger as the increasing of the whole solvent-solute interaction strength, solute size relative to solvent size, and the closeness to the critical density and temperature of the solvent bath. When the attractive solvent-solute interaction becomes large enough and the bulk state moves close enough to the critical temperature of the solvent bath, the maximum solvent accumulation number as a function of solvent bath bulk density appears near the solvent bath critical density; the appearance of this maximum is in contrast with a conclusion drawn by a previous investigation based on an inhomogeneous version of Ornstein-Zernike integral equation carried out only for a smaller parameter space than that in the present paper. Advantage of the DFT approach over the integral equation is discussed.
一种最近提出的分区密度泛函（DF）近似方法（《物理评论E》2003年，第68卷，061201）与一种基于拉格朗日定理的无可调参数版DF近似方法（LTDFA：《物理快报A》2003年，第319卷，279）相结合，提出了一种用于非均匀 Lennard-Jones（LJ）流体的DF近似方法。对于围绕大LJ溶质粒子或硬核 Yukawa 粒子的局部LJ溶剂密度不均匀性，当前DF近似方法的预测结果与现有模拟数据吻合良好。利用当前的DF近似方法，对溶剂浴温度、溶剂 - 溶质相互作用范围、溶剂 - 溶质相互作用强度以及溶质尺寸对局部溶剂密度不均匀性的影响进行了广泛研究。研究发现，溶剂累积数作为溶剂浴体密度函数的一个平台是由于溶剂 - 溶质相互作用与溶剂相关性之间的耦合，其数学表达式是DF理论形式密度分布方程中出现的卷积积分。随着整个溶剂 - 溶质相互作用强度、溶质尺寸相对于溶剂尺寸的增加以及接近溶剂浴的临界密度和温度，这种耦合变得更强。当吸引性的溶剂 - 溶质相互作用变得足够大且体相状态足够接近溶剂浴的临界温度时，溶剂累积数作为溶剂浴体密度函数的最大值出现在溶剂浴临界密度附近；这一最大值的出现与之前基于仅在比本文更小参数空间内进行的非均匀Ornstein-Zernike积分方程的一项研究所得出的结论形成对比。讨论了密度泛函理论方法相对于积分方程的优势。
