在使用经典密度泛函理论进行界面自由能计算时考虑纳米薄膜的贡献
Accounting for Nanofilm Contributions in Interfacial Free Energy Calculations Using Classical Density Functional Theory
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中文总结 AI 辅助
研究流体纳米薄膜在经典密度泛函理论中处理不完整的问题，基于PC-SAFT构建cDFT框架研究其界面性质，建立IFE计算框架，纳入纳米薄膜贡献，该框架为理解相关界面过程提供分子水平基础，与传统方法有差异。
中文摘要 AI 辅助
流体纳米薄膜在纳米尺度界面热力学中起着基础性作用，但其在经典密度泛函理论（cDFT）中的处理仍不完整。我们使用基于扰动链统计缔合流体理论（PC-SAFT）构建的cDFT框架，研究流体-流体和流体-固体界面系统中的纳米薄膜界面性质。与分子模拟的比较表明，关于独立纳米薄膜的长期数值差异在PC-SAFT泛函预测中仍然存在，支持了它们源于热毛细波波动而非密度泛函本身缺陷的观点。重要的是，我们建立了一个界面自由能（IFE）计算的热力学一致框架，明确纳入纳米薄膜热力学贡献，并通过排除固相区域重新定义有效流体体积。所提出的方法与基于流体系统中IFE和分离压力关系的另一种方法具有出色的一致性，而流体-流体和流体-固体的IFE与传统方法预测的有很大不同。我们发现忽略纳米薄膜贡献会在半圆柱形液滴的IFE和接触角中引起显著的尺寸依赖性变化，这与大量文献不一致。不同方法还导致强疏液表面上半球形氩纳米液滴的线张力符号相反。所提出的框架为理解涉及纳米薄膜的界面过程提供了统一的分子水平基础，包括润湿、成核、吸附以及其他依赖于IFE准确评估的现象。
英文摘要
Fluid nanofilms play a fundamental role in nanoscale interfacial thermodynamics, yet their treatment in classical density functional theory (cDFT) remains incomplete. We investigate nanofilm interfacial properties using a cDFT framework built upon the perturbed-chain statistical associating fluid theory (PC-SAFT) for both fluid-fluid and fluid-solid interfacial systems. Comparison with molecular simulations shows that the long-standing numerical discrepancies regarding free-standing nanofilms persist in the PC-SAFT functional predictions, supporting the view that they stem from thermal capillary-wave fluctuations rather than deficiencies of the density functional itself, as such fluctuations are inherently neglected in the mean-field approximation adopted by standard cDFT. Importantly, we establish a thermodynamically consistent framework for interfacial free energy (IFE) calculation, which explicitly incorporates nanofilm thermodynamic contributions and redefines the effective fluid volume by excluding the solid-phase region. The proposed method exhibits excellent consistency with another method based on the relationship between IFE and disjoining pressure for fluid systems, while both fluid-fluid and fluid-solid IFEs differ substantially from those predicted by the conventional method. We find that neglecting nanofilm contributions induces prominent size-dependent variations in the IFE and contact angle of hemicylindrical droplets, which is inconsistent with the extensive literature. Different methods also lead to opposite signs of the line tension for a hemispherical argon nanodroplet on a strongly lyophobic surface. The proposed framework provides a unified molecular-level basis for understanding interfacial processes involving nanofilms, including wetting, nucleation, adsorption, and other phenomena that rely on the accurate evaluation of IFEs.
