8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.17Calculation of van der Waals forces on the basis ofmicroscopic approach with accounting for themany-body interactionsLudmila Boinovich, 1 Kirill Emelyanenko, 1 and Alexandre Emelyanenko 11 A. N. Frumkin Institute of Physical Chemistry and Electrochemistry, Leninsky prospect 31,119991, Moscow, Russian FederationVan der Waals forces result from electrodynamic interactions between the bodies separated by athin interlayer. They bear a universal character, acting between the bodies with any chemical natureand represent one of the strongest type of interactions at small separations. Two main approachesare used for the calculation of these forces. The microscopic approach was developed by Hamakeron the basis of London theory for interactions between separate atoms. In the macroscopic theory,formulated by Dzyaloshinsky, Lifshitz and Pitaevsky, the interaction between two bodies isconsidered as a result of interaction between fluctuating electromagnetic fields. Both approachesare valid within definite restrictions, which do not allow their application for calculation of forcesbetween nanosize particles or for the analysis of surface forces in very thin films. However the accountingfor the many-body interactions in the frame of microscopic approach allows one to treatthe van der Waals interactions in abovementioned systems adequately. To realize this approach wehave adopted the coupled oscillating dipoles method. In this method the van der Waals interactionsare calculated by direct summation of many-atom interactions. We applied this approach to computevan der Waals forces between nanoparticles with various shapes and sizes. We have studiedboth the symmetric systems including similar cubes, spherical particles, crossed and parallel rods,and asymmetric, like plane monolayer and cube, dissimilar cubes etc. The role of the boundaryeffects associated with various relative positions of particles was evaluated as well. Other problemaddressed in our study was related to the peculiarities of van der Waals interactions in free liquidfilms and in wetting films for the case of film thicknesses of order of a few monolayers, includingincomplete monolayers for wetting films.17