TITLE

Thermodynamical, structural, and clustering properties of a microemulsion model

AUTHOR(S)
Skaf, Munir S.; Stell, George
PUB. DATE
November 1992
SOURCE
Journal of Chemical Physics;11/15/1992, Vol. 97 Issue 10, p7699
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
A lattice version of the microemulsion model introduced by A. Ciach, J. Ho\ye, and G. Stell [J. Phys. A 21, L111 (1989)] (CHS) is studied within a mean-field approximation. In the absence of (orientational) surfactant–surfactant interactions, an exact integration of the amphiphiles’ orientational degrees of freedom in the CHS model yields an effective spin-one Hamiltonian with multibody, temperature-dependent interactions between particles, closely resembling the model introduced by M. Schick and W. H. Shih [Phys. Rev. Lett. 59, 1205 (1987)] and subsequently studied by Gompper and Schick. The phase diagram for the CHS effective Hamiltonian on a two-dimensional lattice is calculated at a mean-field level. Comparisons with selected results from Schick’s model are then discussed. The calculated structure functions are in qualitative agreement with experimental results, showing a structural evolution from water-in-oil, to bicontinuous, to oil-in-water microemulsions as the water-to-oil concentration ratio is varied. The symmetric (ρW=ρO) subspace of the disordered phase of both models is then investigated using a percolation theory previously introduced by the authors. In both models the bicontinuous microemulsion phase is identified as a region of the phase diagram where the three molecular species are simultaneously percolating. Finally, the percolation threshold lines are investigated, for both models, as functions of their energy couplings. We find, again, similar behavior for the CHS effective Hamiltonian and Schick Hamiltonian. However, the thresholds are found to be more sensitive to the amphiphilic strength of the surfactant in the former.
ACCESSION #
7644889

 

Related Articles

  • A mean-field theory of grain boundary segregation. Alba, William L.; Whaley, K. Birgitta // Journal of Chemical Physics;9/15/1991, Vol. 95 Issue 6, p4427 

    This paper presents a mean-field solution for a one-dimensional spin Hamiltonian in the presence of spatially varying interactions and external field. In a binary alloy, such inhomogeneous interactions appear in the presence of a grain boundary. We derive the model and place it in the context of...

  • On the Solution of the Number-Projected Hartree—Fock—Bogolyubov Equations. Sheikh, J. A.; Lopes, E.; Ring, P. // Physics of Atomic Nuclei;Mar2001, Vol. 64 Issue 3, p477 

    The numerical solution of the recently formulated number-projected Hartree-Fock-Bogolyubov (HFB) equations is studied in an exactly solvable cranked-deformed shell-model Hamiltonian. It is found that the solution of these number-projected equations involves similar numerical effort as that of...

  • The role of fluctuations in spontaneous metamagnetism. Tuszynski, J. A.; Smith, A. P. // Journal of Applied Physics;11/15/1988, Vol. 64 Issue 10, p5633 

    Examines a Landau-Ginzburg Hamiltonian involving coupled sublattice magnetization as order parameters for spontaneous metamagnets. Information on mean field solutions; Data on the possible phase transitions and the associated conditions.

  • Comparison of several tetrahedra-based lattices. Elhajal, Maged; Canals, Benjamin; Lacroix, Claudine // Canadian Journal of Physics;Nov2001, Vol. 79 Issue 11/12, p1353 

    A comparison of the quantum Heisenberg anti-ferromagnetic model on the pyrochlore lattice, the checkerboard lattice, and the square lattice with crossing interactions is performed. The three lattices are constructed with the same tetrahedral unit cell and this property is used to describe the...

  • Monte Carlo study of a microscopic lattice model for microemulsions. Stockfisch, Thomas P.; Wheeler, John C. // Journal of Chemical Physics;10/15/1993, Vol. 99 Issue 8, p6155 

    A microscopic lattice model of microemulsion-forming ternary solutions has been studied by Monte Carlo simulation. Compelling evidence for three-phase equilibrium among oil-rich, water-rich, and bicontinuous microemulsion phases is reported. The simple two-surfactant bending energy term used in...

  • Reply to ‘‘Comments on Ising-type models for microemulsions and micellar solutions’’. Dawson, K. A.; Lipkin, M. D.; Widom, B. // Journal of Chemical Physics;11/15/1987, Vol. 87 Issue 10, p6211 

    Presents a reply to questions on the effect of fluctuations which are neglected in a mean field study of a lattice model of microemulsions. Difference between the phase diagrams of the lattice model in two and three dimensions.

  • Low dimensional features of the Hamiltonian Mean Field model. Facchini, Angelo; Ruffo, Stefano // AIP Conference Proceedings;1/11/2008, Vol. 970 Issue 1, p109 

    The order parameter of the Hamiltonian Mean Field (HMF) model, which describes the motion of N globally coupled rotors, is a two-component vector (Mx = ΣiN cos(θi)/N,My = ΣiN sin(θi)/N). Its dynamics is found to be “cyclic”: the vector approaches a fixed norm and rotates...

  • Locally enhanced sampling in free energy calculations: Application of mean field approximation to accurate calculation of free energy differences. Verkhivker, Gennady; Elber, Ron; Nowak, Wieslaw // Journal of Chemical Physics;11/15/1992, Vol. 97 Issue 10, p7838 

    Mean field approximation is employed for accurate calculation of free energy differences. Significantly enhanced sampling is obtained for local changes. In an example for the mutation of a residue in a protein, the increase in the sampling yielded converged results at a significantly lower...

  • Interplay between Charge and Magnetic Orderings in the Zero-Bandwidth Limit of the Extended Hubbard Model for Strong On-Site Repulsion. Kapcia, K.; Kłobus, W.; Robaszkiewicz, S. // Acta Physica Polonica, A.;May/Jun2012, Vol. 121 Issue 5/6, p1032 

    A simple effective model of charge ordered and (or) magnetically ordered insulators is studied. The tight binding Hamiltonian analyzed consists of (i) the effective on-site interaction U, (ii) the intersite density-density interaction W and (iii) intersite magnetic exchange interaction Jz (or...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics