Van der Waals forces in free and wetting liquid films

Abstract

Van der Waals interactions induced by fluctuations of electromagnetic field bear universal nature and act between individual atoms, condensed particles or bodies of any type. Continuously growing interest to theoretical understanding as well as to precise evaluation of van der Waals forces is caused by their fundamental role in many physical, chemical, and biological processes. In this paper, we scrutinize progress in the studies of van der Waals forces, related to recent active development of Coupled Dipole Method (CDM) for the analysis of the behavior and properties of nanosized systems. The application of CDM for the analysis of thin liquid films allowed achieving substantial progress in understanding the behavior of free and wetting films. It was shown that both the macroscopic properties, such as excess free energy and Hamaker constants and the local microscopic parameters, such as polarizabilities, can be successfully calculated based only on properties of individual molecules. The impact of lateral film confinement on the specific excess free energy and the film stability was elucidated, and effect of spatial constraints on the spectrum of vibrational states for liquid film and the underlying substrate was analyzed. It was shown that van der Waals interactions between molecules represent the universal mechanism for dynamic structuring and formation of boundary layers and that the CDM allows self-consistently calculating the properties of these layers in both solid and liquid phases.

Keywords: Boundary layer; Coupled dipole method; Dispersion forces; Dzyaloshinskii-Lifshitz-Pitaevskii theory; Many-body interactions; Surface forces.