The concept of mean potentials is used for calculating the free energy and chemical potential dis... more The concept of mean potentials is used for calculating the free energy and chemical potential distribution in a crystalline nonhomogeneous medium, taking into account Coulomb interactions. The lattice version of the equations determining the mean potentials is considered. The closed system of algebraic equations for the mean potentials is formulated and solved. The interparticle interaction potential is split into a short range part, screened Coulomb interaction and the rest of long range Coulomb interaction. The former two interactions are considered in detail, while the long range part is suggested to take into account in the mean spherical approximation. The chemical potential on a given site depends on the concentration distribution over the whole system.
... More recently the results of the AMSA, supplemented by the Ebeling–Grigo choice for the degre... more ... More recently the results of the AMSA, supplemented by the Ebeling–Grigo choice for the degree of association, have been used for the description of the ... We would like to thank Professors George Stell, Lesser Blum, and Vojko Vlachy for several very useful discussions. ...
We investigate the impact of confinement and density field fluctuations on equilibrium properties... more We investigate the impact of confinement and density field fluctuations on equilibrium properties of simple and anisotropic fluids. A field theory formalism is applied to systems with Yukawa-like potentials and Maier-Saupe nematogenic fluids in the bulk and in the vicinity of a hard wall. For Yukawa and two-Yukawa fluids at a surface, the mean field approximation (MFA) reduces to a system of non-linear differential equations. The exact contact theorem is used to research the consistency of the approximations. Indeed, in the MFA, based on a pressure invariant, the contact theorem (CT) is verified. Beyond, in the Gaussian approximation, analytical expressions for density profiles, adsorption coefficient, and free energy are derived. Once more, the CT condition is satisfied. Fluctuations lead to density depletion at the wall regardless of the sign of interaction. As a result, for some systems an oscillatory density profile and a non-monotonous adsorption coefficient as a function of te...
Abstract We study the vapour-liquid phase behaviour of a two-component size-asymmetric ionic flui... more Abstract We study the vapour-liquid phase behaviour of a two-component size-asymmetric ionic fluid confined in a disordered porous matrix formed by uncharged hard spheres (HS) or overlapping (OHS) hard spheres. The ionic fluid is described as a monovalent primitive model consisting of opposite charged hard spheres of different diameters. We propose the theoretical approach which combines the scaled particle theory and the associative mean-spherical approximation based on the simplified mean-spherical approximation. Our results show that the fraction of free ions (dissociation degree) decreases in a matrix. On the other hand, the size asymmetry of ions strengthens this effect and makes it more pronounced at low porosities. It is also observed that the region of phase coexistence of an ionic fluid gets narrower when the porosity of matrices decreases. At the same time, the critical temperature and the critical density get lower. It is shown that the critical parameters of both the symmetrical and asymmetrical ionic fluids confined in the OHS matrix are higher than in the HS matrix if the porosity is fixed.
The concept of mean potentials is used for calculating the free energy and chemical potential dis... more The concept of mean potentials is used for calculating the free energy and chemical potential distribution in a crystalline nonhomogeneous medium, taking into account Coulomb interactions. The lattice version of the equations determining the mean potentials is considered. The closed system of algebraic equations for the mean potentials is formulated and solved. The interparticle interaction potential is split into a short range part, screened Coulomb interaction and the rest of long range Coulomb interaction. The former two interactions are considered in detail, while the long range part is suggested to take into account in the mean spherical approximation. The chemical potential on a given site depends on the concentration distribution over the whole system.
... More recently the results of the AMSA, supplemented by the Ebeling–Grigo choice for the degre... more ... More recently the results of the AMSA, supplemented by the Ebeling–Grigo choice for the degree of association, have been used for the description of the ... We would like to thank Professors George Stell, Lesser Blum, and Vojko Vlachy for several very useful discussions. ...
We investigate the impact of confinement and density field fluctuations on equilibrium properties... more We investigate the impact of confinement and density field fluctuations on equilibrium properties of simple and anisotropic fluids. A field theory formalism is applied to systems with Yukawa-like potentials and Maier-Saupe nematogenic fluids in the bulk and in the vicinity of a hard wall. For Yukawa and two-Yukawa fluids at a surface, the mean field approximation (MFA) reduces to a system of non-linear differential equations. The exact contact theorem is used to research the consistency of the approximations. Indeed, in the MFA, based on a pressure invariant, the contact theorem (CT) is verified. Beyond, in the Gaussian approximation, analytical expressions for density profiles, adsorption coefficient, and free energy are derived. Once more, the CT condition is satisfied. Fluctuations lead to density depletion at the wall regardless of the sign of interaction. As a result, for some systems an oscillatory density profile and a non-monotonous adsorption coefficient as a function of te...
Abstract We study the vapour-liquid phase behaviour of a two-component size-asymmetric ionic flui... more Abstract We study the vapour-liquid phase behaviour of a two-component size-asymmetric ionic fluid confined in a disordered porous matrix formed by uncharged hard spheres (HS) or overlapping (OHS) hard spheres. The ionic fluid is described as a monovalent primitive model consisting of opposite charged hard spheres of different diameters. We propose the theoretical approach which combines the scaled particle theory and the associative mean-spherical approximation based on the simplified mean-spherical approximation. Our results show that the fraction of free ions (dissociation degree) decreases in a matrix. On the other hand, the size asymmetry of ions strengthens this effect and makes it more pronounced at low porosities. It is also observed that the region of phase coexistence of an ionic fluid gets narrower when the porosity of matrices decreases. At the same time, the critical temperature and the critical density get lower. It is shown that the critical parameters of both the symmetrical and asymmetrical ionic fluids confined in the OHS matrix are higher than in the HS matrix if the porosity is fixed.
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