卷 81, 编号 1 (2019)

The Irving–Kirkwood pressure tensor and the pair potential of dispersion forces without retardation have been employed to calculate the local normal pressure on the end surface of a nanodisk, which faces an infinite planar solid surface and is located at some distance from the latter. Analytical and numerical methods have been used to study the dependences of the normal pressure on nanodisk radius and thickness, as well as on the distance between the nanodisk and the solid surface. The small contribution from the disk lateral surface to the total interaction force has been evaluated by comparing the total interaction forces between the nanodisk and the solid surface calculated, on the one hand, by the Hamaker method and, on the other hand, by integrating the local pressure at the end face of the nanodisk.

Data have been presented on the electrical polarizability and surface conductivity of goethite particles in aqueous polydisperse systems. The polarizability of the particles has been experimentally studied by the electrooptical method. Functions of particle distribution over polarizability anisotropy values and sizes have been found. For suspensions containing an electrolyte (KCl), dependences of polarizability anisotropy of the particles on electric field frequency have been experimentally determined in a frequency range of 500 Hz to 2.5 MHz. In addition, dependences of polarizability anisotropy and surface conductivity of the particles on KCl concentration in suspensions have been found. These dependences have shown that the particle polarizability decreases and the surface conductivity increases with a rise in KCl concentration. The surface conductivity of the particles varies in proportion to KCl concentration.

For two-dimensional structures, the linear and point energies are physical parameters of the same significance as the surface and linear energies, respectively, for three-dimensional bodies. The theory presented in this communication enables one to calculate the contribution of dispersion forces to the local cohesion energy, local linear energy, and point energy of graphene from its microscopic parameters, namely, the lattice spacing, two-dimensional atomic density, and pair interaction potential. The local values are calculated on the basis of the Irving–Kirkwood pressure tensor inside of a plane-parallel empty two-dimensional slit with a finite size extension between two rectangular pieces of graphene lying in the same plane. The calculation is performed for the absolute zero of temperature (when the energy is equivalent to the free energy). The structure of graphene is assumed to be rigid, which entails ignorance of the effect of relaxation upon the separation of the two graphene pieces. The calculation result depends on the direction of graphene boundary line. The line normal to the σ-bonds has been selected for the calculations, with this line corresponding to the natural boundary of graphene. The linear and point energies of graphene are calculated within the model of rigid spheres with dispersion forces and the Lennard—Jones model. It has been found that, near a corner of a rectangular graphene piece, the linear energy becomes a value variable within five distances between atoms in the lattice, thereby making it possible to evaluate the contribution of the dispersion forces to the point energy of graphene.

The Monte Carlo method has been employed to carry out computer simulation of condensed water phase nuclei on a basal face of a silver iodide crystal at temperatures of 260 and 400 K. Comparison between the calculated spatial correlation functions of molecules located on nanostructured and smooth substrates has indicated a destructive action of the electric field of the nanostructure on molecular clusters. At the initial stage of absorption, vapor molecules are retained on the nanostructured surface without the formation of interparticle bonds; therewith, initially absorbed molecules are bonded to the structured substrate substantially more strongly than to the smooth surface, on which intermolecular interactions play a significant role in their retention. The electric field of the nanostructured surface has a destructive effect on intermolecular hydrogen bonds. The temperature dependence of the number of hydrogen bonds exhibits an inverse pattern, at which an increase in the temperature within some region of conditions is accompanied by the recovery of some bonds rather than their rupture. A simplified model has been proposed to explain this effect.