Interplay of complete wetting, critical adsorption, and capillary condensation

Abstract

The excess adsorption Γ in two-dimensional Ising strips (∞ × L) subject to identical boundary fields, at both one-dimensional surfaces decaying in the orthogonal direction j as −h1j −p , is studied for various values of p and along various thermodynamic paths below the critical point by means of the density-matrix renormalization-group method. The crossover behavior between the complete wetting and critical adsorption regimes, occurring in semi-infinite systems, are strongly influenced by confinement effects. Along isotherms T = const the asymptotic power law dependences on the external bulk field, which characterize these two regimes, are undercut by capillary condensation. Along the pseudo first-order phase coexistence line of the strips, which varies with temperature, we find a broad crossover regime where both the thickness of the wetting film and Γ increase as function of the reduced temperature τ but do not follow any power law. Above the wetting temperature the order parameter profiles are not slab-like but exhibit wide interfacial variations and pronounced tails. Inter alia, our explicit calculations demonstrate that, contrary to opposite claims by Kroll and Lipowsky [Phys. Rev. B 28, 5273 (1983)], for p = 2 critical wetting transitions do exist and we determine the corresponding wetting phase diagram in the (h1, T ) plane.

Magnetization-based assessment of correlation energy in canted single-chain magnets

“…As the Hilbert space dimension increases exponentially with increasing Trotter number, computations are feasible only for relatively small M . To overcome this problem, we employ the Density-Matrix Renormalization Group technique (DMRG) [27][28][29][30][31] for determining an effective Hamiltonian representation in the Hilbert subspace of a given size m which ensures covering the entire experimental temperature range.…”

Fluid–Fluid Transitions at Bulk Supercritical Conditions

“…[1][2][3][4][5][6][7] The presence of surfaces leads * To whom correspondence should be addressed 1 to a truncation of the range of intermolecular potentials, thus weakening fluid-fluid interactions adjacent to them. In a pore, weakening of fluid interactions has a similar impact on the phase diagram that an increased temperature has in the bulk.…”

Analysis of the susceptibility in a fluid system with Neumann – plus boundary conditions

“…We are looking for real-valued solutions of Eq. (5), corresponding to given values of the parameters τ and h, which are smooth in the open interval (0, 1), and satisfy the Neumann-infinity boundary conditions (9). In the case of (+∞, +∞) boundary conditions, analytical results for the order parameter and the local and total susceptibilities are presented in our previous paper [15].…”

“…For a simple fluid or for binary liquid mixtures the wall generically prefers one of the fluid phases or one of the components. In the vicinity of the bulk critical point the last leads to the phenomenon of critical adsorption [3][4][5][6][7][8][9][10][11][12][13]. This can be modelled by considering local surface field h 1 acting solely on the surfaces of the system.…”