用密度泛函理论研究Lennard-Jones流体在狭缝中的相平衡

Investigation of Phase Equilibria for Lennard-Jones Fluid in Slit Pores by Density Functional Theory

用改进的基础度量理论(modifiedfundamentalmeasuretheory,MFMT)和密度Taylor展开分别表达过剩自由能中的短程作用和色散作用.流体分子与狭缝壁之间的相互作用以10-4-3势能函数表达.由巨势最小原理确定Lennard-Jones(LJ)流体在狭缝中的密度分布和过剩吸附量,所得结果与分子模拟数据吻合良好.根据平衡时两相温度,化学势及巨势相等,计算了LJ流体在狭缝中的相平衡.

The excess Helmholtz free energy functional was formulated in terms of a modified fundamental measure theory （MFMT） for short ranged repulsion while a functional Taylor expansion for long ranged attractions. The interaction between fluid molecules and the pore wall was expressed by the 10-4-3 potential. The density profiles and the excess adsorption for Lennard-Jones （LJ） fluid inside slit pores were determined by minimizing the grand potential and the results agreed well with the simulation data. The phase equilibria for LJ fluid confined in slit pores were calculated according to the requirement that temperature, chemical potential and grand potential in both phases should be equal.