Ustinov E A, Do D D
Department of Chemical Engineering, University of Queensland, St. Lucia, Queensland, Brisbane, 4072 Australia.
J Phys Chem B. 2005 Jun 16;109(23):11653-60. doi: 10.1021/jp050823g.
In this paper, we present an analysis of argon adsorption in cylindrical pores having amorphous silica structure by means of a nonlocal density functional theory (NLDFT). In the modeling, we account for the radial and longitudinal density distributions, which allow us to consider the interface between the liquidlike and vaporlike fluids separated by a hemispherical meniscus in the canonical ensemble. The Helmholtz free energy of the meniscus was determined as a function of pore diameter. The canonical NLDFT simulations show the details of density rearrangement at the vaporlike and liquidlike spinodal points. The limits of stability of the smallest bridge and the smallest bubble were also determined with the canonical NLDFT. The energy of nucleation as a function of the bulk pressure and the pore diameter was determined with the grand canonical NLDFT using an additional external potential field. It was shown that the experimentally observed reversibility of argon adsorption isotherms at its boiling point up to the pore diameter of 4 nm is possible if the potential barrier of 22kT is overcome due to density fluctuations.
在本文中，我们借助非局部密度泛函理论（NLDFT）对具有无定形二氧化硅结构的圆柱形孔隙中的氩吸附进行了分析。在建模过程中，我们考虑了径向和纵向密度分布，这使我们能够在正则系综中考虑由半球形弯月面分隔的类液和类气流体之间的界面。确定了弯月面的亥姆霍兹自由能作为孔径的函数。正则NLDFT模拟展示了类气和类液旋节线处密度重排的细节。还通过正则NLDFT确定了最小桥和最小气泡的稳定性极限。利用附加的外部势场，通过巨正则NLDFT确定了成核能量作为体相压力和孔径的函数。结果表明，如果由于密度涨落克服了22kT的势垒，那么在沸点下氩吸附等温线在孔径达4nm时实验观察到的可逆性是可能的。
