平行硬壁间荷电硬球流体的密度泛函理论研究

基于经典流体的密度泛函理论并结合改进的基本度量理论, 研究了受限于平行硬壁间的荷电硬球流体的平衡密度分布. 通过对比有、无外电场时分子数密度分布的相应变化情况, 分析了荷电硬球分子间的库仑排斥势能与场致势能间的竞争作用, 研究了电场对于受限荷电硬球流体系统聚集态结构的影响.     

受限混合物溶剂中胶粒的耗尽势及吸附稳定性

基于密度泛函理论和Yvon-Born-Green方程得到了胶粒耗尽势的表达式.采用密度泛函理论计算了单壁附近和平行狭缝中的混合物溶剂中胶粒的耗尽势及其在单壁处的吸附稳定性.研究结果表明,不同溶剂组分的体积分数和粒子尺寸比等因素对胶粒耗尽势的强度、力程和周期均可产生显著影响,胶粒在单壁附近的吸附稳定性与溶剂粒子尺寸比和体积分数密切相关.此外,对受限于平行狭缝的胶体悬浮液,胶粒的耗尽势阱还可随粒子尺寸比和缝宽呈振荡趋势变化.     

Structural and thermodynamic properties of inhomogeneous fluids in rectangular corrugated nano-pores

Based on the free-energy average method, an area-weighted effective potential is derived for rectangular corrugated nano-pore. With the obtained potential, classical density functional theory is employed to investigate the structural and thermodynamic properties of confined Lennard-Jones fluid in rectangular corrugated slit pores. Firstly, influence of pore geometry on the adsorptive potential is calculated and analyzed. Further, thermodynamic properties including excess adsorption, solvation force, surface free energy and thermodynamic response functions are systematically investigated. It is found that pore geometry can largely modulate the structure of the confined fluids, which in turn influences other thermodynamic properties. In addition, the results show that different geometric elements have different influences on the confined fluids. The work provides an effective route to investigate the effect of roughness on confined fluids. It is expected to shed light on further understanding about interfacial phenomena near rough walls, and then provide useful clues for the design and characterization of novel materials.     

Species separation of binary colloidal mixtures in the multi-Gauss potential: Effect of depletion

For the asymmetrical colloidal mixture subject to a confining potential and an external multi-Gauss potential, the separation of species is studied based on the classical density functional theory of simple fluids. The multi-Gauss potential consists of several Gauss barriers, which are distributed along the axial direction with uniform distance. The barrier width,barrier distance, and barrier height are individually adjusted to investigate their effects on the species separation. From the numerical results, it is concluded that in each condition, the competition between the external potential and the depletion potential determines the phase equilibrium and the separation. Species separation appears only in the region where the depletion is dominant. On the contrary, both species are absent in the regions where the external potential takes the absolute advantage.     

Density functional study of the pressure tensor for inhomogeneous Lennard—Jones fluids

Based on classical density functional theory,an expression of the pressure tensor for inhomogeneous fluids is presented.This takes into account greater correlation between particles,especially for systems that are geometrically confined or involve an interface.The density and pressure components of Lennard-Jones fluids confined in hard and softened nano-cavities are calculated.A comparison between the results of this work and IK expression suggests that the agreement depends on temperature.The interfacial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large.The results of the solid-fluid interfacial tension for Lennard-Jones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.     

平行板间超支化聚合物流体的密度分布和溶剂化力

在密度泛函理论(DFT)框架下,应用改进的基本度量理论(MFMT)和统计力学理论结合加权密度近似(WDA)分别表示硬球作用和聚合作用对自由能泛函的贡献,建立了描述ABg型超支化聚合物流体的化学势,得到了聚合物流体在平行板间的密度分布表达式,计算了聚合物流体在两平行板间的密度分布,并探讨了体积分数、反应程度和单体中B类官能团数对体系密度分布的影响.此外,通过体系密度分布,进一步分析了反应程度、板间宽度与溶剂化力的关系.     

Henry范围内粗糙孔隙中气体的等量吸附热与吸附选择性

Henry系数和等量吸附热是表征气体吸附中气-固作用的重要参数.为了更好地理解气体在粗糙孔隙中的吸附特征,首先构造并计算了矩形波纹粗糙狭缝及其外势分布.进一步,采用经典统计力学研究了狭缝中H₂分子在低压范围内的纵向Henry系数和等量吸附热.研究结果表明,粗糙狭缝的几何形貌和基板间距等因素可对狭缝中气体的纵向Henry系数和等量吸附热产生显著的影响与调制作用.进一步,在Henry范围内计算了CO₂/H₂二元混合物气体在矩形波纹粗糙狭缝中的吸附选择性,并研究了狭缝几何形貌的调制作用.此外,还研究了不同形状的凸起对气体吸附性质的影响.相关的结果可为理解多孔材料中气体的吸附、分离和提纯等过程提供可靠的理论依据,并有望为设计与研发新型纳米功能材料提供有益的参考.     

Density Functional Theory Approach for Charged Hard Sphere Fluids Confined in Spherical Micro-Cavity

Within the framework of the density functional theory for classical fluids, the equilibrium density profiles of charged hard sphere fluid confined in micro-cavity are studied by means of the modified fundamental measure theory. The dimension of micro-cavity, the charge of hard sphere and the applied electric field are found to have significant effects on the density profiles. In particular, it is shown that Coulomb interaction, excluded volume interaction and applied electric field play the central role in controlling the aggregated structure of the system.     

荷电流体中静电关联效应的有效势模型

基于Nordholm关于等离子体的库仑关联孔穴的概念,提出了描述荷电流体的有效库仑势模型.采用经典密度泛函理论,计算了受限于纳米微腔中荷电流体的平衡结构.通过对比计算结果,研究了粒子间的关联效应对体系平衡密度分布和剩余吸附量的影响.此外,计算并研究了较大尺寸受限空间中荷电粒子的关联效应对体系结构的影响.研究结果表明:本文提出的有效两体势模型可有效地预测荷电粒子间的库仑关联对体系结构和物理化学性质的影响.研究结果可为研究和理解其他复杂的势模型体系中的关联效应提供可能的线索.