Screening Effects on van der Waals Interactions
作者单位：Shanghai University University of Technology Sydney Griffith University
会议名称：《第十三届全国量子化学会议》
会议日期：2017年
学科分类：081704[工学-应用化学] 07[理学] 070304[理学-物理化学(含∶化学物理)] 08[工学] 0817[工学-化学工程与技术] 0703[理学-化学]
关 键 词：Van der Waals interaction Non-additive effect Long-range Fluctuation
摘 要：Van der Waals interactions are ubiquitous in the world, and have been recognized as critical to most important properties of natural matters including proteins and DNA(deoxyribonucleic acid). In chemical and biochemical envi ronments,mode rn empirical app ro aches like Grimme ’s D3 method allow for fast evaluation of these forces in electronic-structure calculations. However, this and related methods are based on London’s approximation to the van der Waa ls force as arising from pairwise-additive atomic fluctuations and polarizations. Recently,the Dobson classification was introduced to understand the shortcomings of such approaches, shortcomings particularly relevant for low-dimensional molecules and conductors such as graphene, C, large aromatic molecules, and nanotubes. An important experimental characterisation of non-additive effects was the recent demonstration the placing a graphene layer between a silica substrate and silica AFM tip switches off the van der Waals inter action between tip and substrate through a Faraday-cage screening effect. We develop computational models to understand this effect, comparing the pairwise-additive D3 method to the popular many-bond dispersion(MBD) method for treating screening, and a new method developed by Gould to include and improve not only these contributions but also those from long-range fluctuations(related to the Casimir effect).