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arXiv 1708.01299physics.chem-phcond-mat.stat-mech
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原子液体中的溶剂化:高斯场论与密度泛函理论的联系

Solvation in atomic liquids: connection between Gaussian field theory and density functional theory

V. Sergiievskyi, M. Levesque, B. Rotenberg, D. Borgis

摘要:

对于分子溶剂化的问题,表示为一种液体,该液体受到由溶解在该溶剂中的任意形状的分子溶质产生的外部势场的作用,我们在David Chandler [Phys. Rev. E,1993,48,2898]导出的高斯场论和经典的密度泛函理论之间建立了联系。我们表明,钱德勒关于任意形状硬核解的结果可以通过使用辅助拉格朗日乘子场最小化线性化HNC泛函以在核心内部施加消失的密度来恢复,或者通过最小化直接在核心外部的该泛函来恢复-实际上是一个更简单的过程。这些等效的方法相比,DFT的其他两个变种,无论是在HNC,或部分线性化HNC近似,在Lennard-Jones溶剂中的Lennard-Jones溶质的溶剂化的大小增加。与蒙特卡罗模拟相比,所有这些理论对非均匀溶剂结构给出了可接受的结果,但对溶剂化自由能完全超出范围。这可以在DFT中通过向HNC泛函添加硬球桥校正来固定。

英文摘要:

For the problem of molecular solvation, formulated as a liquid submitted to the external potential field created by a molecular solute of arbitrary shape dissolved in that solvent, we draw a connection between the Gaussian field theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical density functional theory. We show that Chandler's results concerning the solvation of a hard core of arbitrary shape can be recovered by either minimising a linearised HNC functional using an auxiliary Lagrange multiplier field to impose a vanishing density inside the core, or by minimising this functional directly outside the core --- indeed a simpler procedure. Those equivalent approaches are compared to two other variants of DFT, either in the HNC, or partially linearised HNC approximation, for the solvation of a Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to Monte-Carlo simulations, all those theories give acceptable results for the inhomogeneous solvent structure, but are completely out-of-range for the solvation free-energies. This can be fixed in DFT by adding a hard-sphere bridge correction to the HNC functional.

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