A. I. Rusanov

The molecular dynamics simulation of a small drop

Abstract Liquid microdrops with the Lennard-Jones potential have been investigated by the molecular dynamics technique. The temperature dependence of energy and the influence of temperature, volume, and the number of molecules on the density profile and the pressure tensor profile have been studied. The surface tension and the radii of the equimolecular surface and the surface of tension have been calculated. The surface tension has been shown to increase when the drop size decreases.

On the thermodynamics of deformable solid surfaces

Abstract The system of thermodynamic fundamental equations for bulk phases and interfaces has been studied within the frames of the completely elastic solid model. The dependence of surface properties on strains has been considered. The deformation of a solid surface at incomplete wetting and the possibility of the contact angle anisotropy have been analyzed. The influence of the bulk strains of a solid on wetting has been discussed.

Reformulation of the thermodynamic theory of nucleation on charged particles

Abstract A complete set of thermodynamic fundamental equations for heterogeneous systems with curved interfaces in an external electric field has been derived recognizing the difference between the mechanical surface tension, γ, and the thermodynamic surface tension, a. Equations have been obtained for the dependence of γ, σ, the phase transition temperature, chemical potentials, and pressure on the surface curvature and an electric field. Extensions of Kelvins and J. J. Thomsons equations have been given. Calculation of the work of nucleation on charged particles and the phase transition activation energy has been carried out. When applied to water condensation, the result obtained shows that negative condensation centers are more active than positive ones.

Dynamic surface properties of water: Surface tension and surface potential

Abstract The dynamic surface tension and surface potential of water have been measured for the surface ages from 0.8 to 7.0 msec. In both cases, the time of establishing the equilibrium values is found to be about 3 msec. The value +0.1 V for the equilibrium surface potential has been obtained by extrapolation. The structure of the surface layer has been discussed.

The molecular dynamics simulation of water clusters

Water clusters containing 15, 27, and 64 molecules have been investigated by molecular dynamics at various temperatures. Profiles for atomic density, the polarization vector, local energy, and the pressure tensor have been obtained. A simple way to calculate the local electric potential as an average Coulomb potential at a sphere of radius r has been offered that resulted in more reliable data. The orientation of water molecules at the surface has been studied in detail. The most probable position of the molecular plane has been shown to be perpendicular and of the dipole vector parallel to the surface. Two models of water molecules with different values of the quadrupole component Qzz along the dipole axis have been considered. The theoretical prediction of the proportionality of the surface potential and Qzz has been confirmed.

Role of surface forces in heterogeneous nucleation on wettable nuclei

Abstract The condition has been formulated and the role of the surface forces at a solid-liquid interface has been established for the barrierless heterogeneous formation of a droplet on a macroscopic wettable insoluble solid nucleus in supersaturated vapour. The threshold value of the vapour supersaturation starting from which heterogeneous nucleation occurs as a barrierless process and all thermodynamic characteristics of heterogeneous formation of a droplet which are necessary for kinetic description of phase transition below the threshold have been found as a function of parameters of the exponential and the power-law approximations to the work of wetting of the nucleus associated with the surface forces and size of condensation nuclei: the coordinates and the half-widths of the potential hump and the potential well in the curve of the work of heterogeneous formation of a droplet; the activation barrier which droplets have to overcome by fluctuations in the process of formation of the stable phase.

Generalization of the Gibbs–Kelvin–Köhler and Ostwald–Freundlich equations for a liquid film on a soluble nanoparticle

A derivation of chemical equilibrium equations for a spherical thin film of solution around a soluble solid nanoparticle is presented. The equations obtained generalize the Gibbs-Kelvin-Kohler and Ostwald-Freundlich equations for a soluble particle immersed in the bulk phase. The generalized equations describe the dependence of the chemical potentials of a condensate and dissolved nanoparticle matter in the thin solution film, the condensate saturated pressure, and the solubility of the nanoparticle matter on the film thickness, and the nanoparticle size with account of the disjoining pressure of the liquid film.

Thermodynamic theory of nucleation on charged particles

Abstract A complete system of thermodynamic fundamental equations for heterogeneous systems with curved interfaces in an external electric field has been derived. Equations have been obtained for the dependence of the surface tension, surface potential, phase transition temperature, equilibrium chemical potential, and vapor pressure on surface curvature and the value of an external field. Calculation of the work of nucleation on charged particles and the phase transition activation energy has been carried out. When applied to the water condensation process, the results obtained show that negative condensation centers are much more active than positive ones. The significance of the theory presented for the understanding of atmospheric processes has been briefly discussed.

Classification of line tension

Abstract The classification of line tension has been given distinguishing between the mechanical line tension and the thermodynamic one as related to the excess mechanical stress at the phase linear boundary and the specific work of formation of a new linear phase boundary, respectively. Three types of line tension are characterised: the line tension in two-dimensional heterogeneous systems, the line tension at the three phase contact line, and the effective line tension in the presence of deformation along the three phase contact line. Phase transitions in two-dimensional systems, the effect of roughness of the three phase contact line and the anisotropy of the contact angle on deformed elastomeric surfaces have been discussed.

New theory of equation of state for surface monolayer

A novel statistical-thermodynamic approach to deriving an equation of state for a surface monolayer has been elaborated on the basis of excluded area. A master differential equation relating surface (two-dimensional) pressure to excluded area has been derived to generate equations of state for a surface monolayer. The crudest solution (the zero approximation) of the master equation reproduces the known van Laar and Frumkin equations of state. The first approximation yields the two-dimensional van der Waals equation. The second, third, and fourth approximations lead to new and more accurate equations of state. The particular result of the fourth approximation is a precise equation of state for hard disks with deviation not more than 0.46% from data obtained by Monte Carlo and molecular-dynamics simulations within the whole range of surface density. The role of the third dimension for surface equations of state is discussed. An orientation equation of state has been proposed for monolayers containing anisometric particles. It follows from the orientation equation obtained that the orientation effect creates possibility for a two-dimensional phase transition.