Confinement of Ar between two identical parallel semi-infinite walls.
Confinement of Ar between two identical parallel semi-infinite walls.
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DOI：
10.1063/1.3306449
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发表时间：
2010-02
期刊：
影响因子：
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通讯作者：
S. A. Sartarelli;L. Szybisz
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文献类型：
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作者：
S. A. Sartarelli;L. Szybisz
在密度泛函理论的框架内研究了Ar在碱金属、碱土金属Mg和CO(2)的两个相同的平行半无限壁的平面狭缝中的限制。假设 (1) 流体原子通过最近提出的有效吸引对势与强度 epsilon(ff) 相互作用，它再现了体共存曲线处液-汽界面表面张力的实验数据，以及 (2) 壁上的吸附由以井深度 W(sf) 为特征的从头计算势来描述。通过这种方式，系统在现实方法的框架内进行了研究。我们发现，对于小覆盖范围，狭缝总是通过形成两个对称的蒸汽膜（每壁一个）来填充。为了增加覆盖率，该行为取决于比率 W(sf)/epsilon(ff) 和温度 T。对于碱金属，我们在吸附物的三相点 T(t) 处发现平均密度 rho(av) (*) 的状态，其中基态表现出不对称密度分布，导致所谓的自发对称破缺 (SSB) 效应。 SSB 在平均密度 rho(sb1) (*) 处出现，在较高平均密度 rho(sb2) (*) 处消失。当 T 增加时，狭缝的密度范围 rho(sb1) (*)T(cpw) 被对称地填充，直到相变到毛细管冷凝。所有这些特征都作为基底强度和狭缝宽度的函数进行检查。此外，未发现 Mg 和 CO(2) 的 SSB 效应。
The confinement of Ar in planar slits of two identical parallel semi-infinite walls of alkali metals, alkaline-earth metal Mg, and CO(2) is investigated within the framework of the density functional theory. It is assumed that (1) the fluid atoms interact via a recently proposed effective attractive pair potential with strength, epsilon(ff), which reproduces the experimental data of the surface tension of the liquid-vapor interface at the bulk coexistence curve, and (2) the adsorption on the walls is described by ab initio potentials characterized by a well depth, W(sf). In this way the systems were studied in the framework of a realistic approach. We found that for small coverages, the slit is always filled by forming two symmetric vapor films, one at each wall. For increasing coverage the behavior depends on the ratio W(sf)/epsilon(ff) and the temperature T. In the case of alkali metals, we found at the triple point, T(t), of the adsorbate a regime of average density rho(av) ( *) in which the ground state exhibits asymmetric density profiles, leading to the so-called spontaneous symmetry breaking (SSB) effect. The SSB appears at an average density rho(sb1) ( *) and disappears at a higher average density rho(sb2) ( *). When T is increased, the range of densities rho(sb1) ( *)T(cpw) the slit is filled symmetrically up to the phase transition to capillary condensation. All these features are examined as a function of the strength of the substrate and the width of the slit. Furthermore, no SSB effect was found for Mg and CO(2).