物理化学学报 >> 2004, Vol. 20 >> Issue (06): 668-672.doi: 10.3866/PKU.WHXB20040624

研究简报 上一篇    

修正的格子空间的密度泛函理论在狭缝中的应用

刘梅堂;牟伯中;刘洪来;胡英   

  1. 华东理工大学化学系,上海 200237
  • 收稿日期:2004-01-19 修回日期:2004-03-03 发布日期:2004-06-15
  • 通讯作者: 牟伯中 E-mail:bzmu@ecust.edu.cn

Application of the Revised Lattice Density Functional Theory in Slits

Liu Mei-Tang;Mu Bo-Zhong;Liu Hong-Lai;Hu Ying   

  1. Department of Chemistry, East China University of Science and Technology, Shanghai 200237
  • Received:2004-01-19 Revised:2004-03-03 Published:2004-06-15
  • Contact: Mu Bo-Zhong E-mail:bzmu@ecust.edu.cn

摘要: 对描述单原子分子溶液在狭缝中的吸附现象的格子空间的密度泛函理论 (LDFT, lattice density functional theory)进行了修正, 在系统Helmholtz函数的推导中引入了平均场近似校正和Gibbs-Helmholtz方程. 对比Monte Carlo (MC)模拟结果, 发现LDFT理论对吸附分子在狭缝中的吸附浓度分布的预测与模拟数据有较大的偏差, 而修正模型的结果与模拟数据吻合较好 .随着体相浓度的变化,分子在狭缝中具有多级吸附行为, 具体表现为在特定体相浓度区, 对相同的体相浓度,狭缝中同时存在不同的分子浓度分布, 而在Gibbs等温线上可以明显看出多级吸附的性质. 对比修正前后的结果发现,两者均可以预测多级吸附行为, 但仍存在着较大的差异.

关键词: LDFT, 狭缝吸附, 多级吸附, 相变

Abstract: The lattice density functional theory (LDFT) was modified for monoatomic molecule adsorption systems in slits, and the revised mean field approximation and Gibbs-Helmholtz equation were introduced into the construction of Helmholtz function. Results of the revised model show a satisfactory consistence with that by Monte Carlo (MC) simulation, whereas the original LDFT data show a large deviation from it. It indicates that the mean field approximation will bring obvious system errors in the original LDFT. Multilevel adsorption occurs in slits, and different density profiles exist at a specific equilibrium concentration. This kind of multilevel adsorption is also clearly shown on the Gibbs isotherm. By comparison of results between the revised and the original LDFT, it is found that both of them can predict the multilevel adsorption behaviors, but there are still large differences between them.

Key words: LDFT, Slit adsorption, Multilevel adsorption, Phase transition