We determine in a mean field approximation the spin-1/2 Ising model line tension tau along the bo... more We determine in a mean field approximation the spin-1/2 Ising model line tension tau along the boundary between surface states at the prewetting transition in the neighborhood of the wetting transition at bulk phase coexistence. We find very close agreement with the predictions of the interface displacement model for short-range interactions, i.e., tau increases (with a square-root dependence on the
Page 1. PHYSICAL REVIEW E VOLUME 47, NUMBER 6 JUNE 1993 Hyperscaling and nonclassical exponents f... more Page 1. PHYSICAL REVIEW E VOLUME 47, NUMBER 6 JUNE 1993 Hyperscaling and nonclassical exponents for the line tension at wetting J.O. Indekeu* and A. Robledo Laboratorium voor Vaste Stof-Fysika en Magnetisme ...
We describe a search for solidlike singlet distribution functions in a system of hard spheres. Th... more We describe a search for solidlike singlet distribution functions in a system of hard spheres. The procedure, which is based on Widom's relation between the activity and the density in a nonuniform fluid, is applied to a sequence of hardcore lattice gases with increasingly extended interactions. When the system is defined on a Bethe lattice we obtain exact solutions for arbitrary external field and size of the hard core. This includes the limit in which the number of excluded neighbors goes to infinity while the lattice spacing is made to vanish. The study of the first few members in this family of models suggests the existence of an infinite sequence, beginning with the next-nearest-neighbor problem, of first-order sublattice ordering transitions occurring before close packing and at zero field. The periodic solutions for the density originate at bifurcation points located at uniform close packing.
We calculate, for a spin-1/2 Ising model within the mean-field approximation, the line tension al... more We calculate, for a spin-1/2 Ising model within the mean-field approximation, the line tension along partial-wetting surface states up to a first-order wetting transition where the line disappears. We likewise calculate the line tension of the boundary between the two coexisting surface states at the prewetting transition and follow its behavior into the neighborhood of bulk wetting. In both cases
We derive the interfacial-curvature free energy for a simple fluid from density-functional theory... more We derive the interfacial-curvature free energy for a simple fluid from density-functional theory, and find a form matching that for a two-dimensional shearless elastic media. The fourth moment of the direct correlation function and the density gradient determine the bending moduli kappa and kappa¯, while the spontaneous curvature c0 is given by asymmetry in the density. We obtain the critical indices of these quantities and corrections to the Laplace equation for curved interfaces.
It is shown that the variational principle for the grand potential of a nonuniform fluid as a fun... more It is shown that the variational principle for the grand potential of a nonuniform fluid as a functional of the singlet density yields the potential distribution theory for the equilibrium density. We derive the explicit form that the functional takes for a system of hard rods, and propose an approximate one for hard spheres. Attractive interactions are also considered in mean-field approximation. In all cases the pair direct correlation function of the nonuniform system is obtained and the density gradient expansion of the free energy is investigated.
The scaling properties of interfacial correlations in the extended capillary-wave model (Romero-R... more The scaling properties of interfacial correlations in the extended capillary-wave model (Romero-Rochín, V., Varea, C., and Robledo, A., 1992, Physica A, 184, 367) are analysed and the procedure developed previously by Weeks and collaborators for studying interfacial correlations is confirmed to apply to the extended case and to reproduce most of the earlier features. In addition to this it is
We determine in a mean field approximation the spin-1/2 Ising model line tension tau along the bo... more We determine in a mean field approximation the spin-1/2 Ising model line tension tau along the boundary between surface states at the prewetting transition in the neighborhood of the wetting transition at bulk phase coexistence. We find very close agreement with the predictions of the interface displacement model for short-range interactions, i.e., tau increases (with a square-root dependence on the
Page 1. PHYSICAL REVIEW E VOLUME 47, NUMBER 6 JUNE 1993 Hyperscaling and nonclassical exponents f... more Page 1. PHYSICAL REVIEW E VOLUME 47, NUMBER 6 JUNE 1993 Hyperscaling and nonclassical exponents for the line tension at wetting J.O. Indekeu* and A. Robledo Laboratorium voor Vaste Stof-Fysika en Magnetisme ...
We describe a search for solidlike singlet distribution functions in a system of hard spheres. Th... more We describe a search for solidlike singlet distribution functions in a system of hard spheres. The procedure, which is based on Widom's relation between the activity and the density in a nonuniform fluid, is applied to a sequence of hardcore lattice gases with increasingly extended interactions. When the system is defined on a Bethe lattice we obtain exact solutions for arbitrary external field and size of the hard core. This includes the limit in which the number of excluded neighbors goes to infinity while the lattice spacing is made to vanish. The study of the first few members in this family of models suggests the existence of an infinite sequence, beginning with the next-nearest-neighbor problem, of first-order sublattice ordering transitions occurring before close packing and at zero field. The periodic solutions for the density originate at bifurcation points located at uniform close packing.
We calculate, for a spin-1/2 Ising model within the mean-field approximation, the line tension al... more We calculate, for a spin-1/2 Ising model within the mean-field approximation, the line tension along partial-wetting surface states up to a first-order wetting transition where the line disappears. We likewise calculate the line tension of the boundary between the two coexisting surface states at the prewetting transition and follow its behavior into the neighborhood of bulk wetting. In both cases
We derive the interfacial-curvature free energy for a simple fluid from density-functional theory... more We derive the interfacial-curvature free energy for a simple fluid from density-functional theory, and find a form matching that for a two-dimensional shearless elastic media. The fourth moment of the direct correlation function and the density gradient determine the bending moduli kappa and kappa¯, while the spontaneous curvature c0 is given by asymmetry in the density. We obtain the critical indices of these quantities and corrections to the Laplace equation for curved interfaces.
It is shown that the variational principle for the grand potential of a nonuniform fluid as a fun... more It is shown that the variational principle for the grand potential of a nonuniform fluid as a functional of the singlet density yields the potential distribution theory for the equilibrium density. We derive the explicit form that the functional takes for a system of hard rods, and propose an approximate one for hard spheres. Attractive interactions are also considered in mean-field approximation. In all cases the pair direct correlation function of the nonuniform system is obtained and the density gradient expansion of the free energy is investigated.
The scaling properties of interfacial correlations in the extended capillary-wave model (Romero-R... more The scaling properties of interfacial correlations in the extended capillary-wave model (Romero-Rochín, V., Varea, C., and Robledo, A., 1992, Physica A, 184, 367) are analysed and the procedure developed previously by Weeks and collaborators for studying interfacial correlations is confirmed to apply to the extended case and to reproduce most of the earlier features. In addition to this it is
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Papers by Alberto Robledo