Marc Baus

Observation, prediction and simulation of phase transitions in complex fluids

Preface. A: Experiment. Phase Transition of Spherical Colloids W.C.K. Poon, P.N. Pusey. Liquid Crystal Phase Transitions in Dispersions of Rodlike Colloidal Particles H.N.W. Lekkerkerker, P. Buining, J. Buitenhuis, G.J. Vroege, A. Stroobants. Phase Transitions in Colloidal Suspensions of Virus Particles S. Fraden. B: Theory. Colloidal Suspensions: Density Functional Theory at Work J.-P. Hansen. Bilayer Phases M.E. Cates. Liquid Crystal Interfaces M.M. Telo Da Gama. Statistical Mechanics of Directed Polymers D.R. Nelson. C: Simulation. Introduction to Monte Carlo Simulation M.P. Allen. Numerical Techniques to Study Complex Liquids D. Frenkel. Molecular Dynamics Techniques for Complex Molecular Systems M. Sprik. Gibbs Ensemble Techniques A.Z. Panagiotopoulos. Phase Transitions in Polymeric Systems K. Binder. Simulations and Phase Behaviour of Liquid Crystals M.P. Allen. D: Seminars. Equilibrium Sedimentation Profiles of Screened Charged Colloids. A Test of the Hard-Sphere Equation of State V. Degiorgio, R. Piazza, T. Bellini. Dynamics of N-Nonadecane Chains in Urea Inclusion Compounds as Seen by Incoherent Quasielastic Neutron Scattering and Computer Simulations M. Souaille, J.C. Smith, A.-J. Dianoux, F. Guillaume. Theory of Phase Equilibria in Associating Systems: Chain and Ring Aggregates, Amphiphiles, and Liquid Crystals R.P. Sear, G. Jackson. Can a Solid be Turned into a Gas Without Passing through a First Order Phase Transition? R. Lovett. Index.

The freezing of hard spheres: The density functional theory revisited

We have analysed the recent theories of freezing and found that all results obtained hitherto are biased numerically by the early truncation of slowly converging series. As a result the local density of the solid is shown to become very negative in the interstitial regions. Therefore we have reconsidered the theory of freezing starting from formally exact equations, making three physical approximations and testing all numerical methods for the case of the freezing of hard spheres. A fluid-solid transition is found which is in fair agreement with the known computer experiments.

The present status of the density-functional theory of the liquid-solid transition

Recent attempts at a microscopic description of the liquid-solid transition, within the density-functional theory of non-uniform fluids, are put into a critical perspective by comparing the different methods proposed and the results obtained for the freezing of hardcore systems.

Statistical Mechanical Theories of Freezing: An Overview

Recent progress in the microscopic description of the liquid-solid coexistence is examined critically and put into historical perspective. The emphasis is on the density functional theories, including some of their more controversial aspects. The underlying physical freezing mechanism is discussed in detail.

Computer simulation study of the local pressure in a spherical liquid–vapor interface

The pressure profiles across a liquid–vapor interface introduced previously [J. Chem. Phys. 106, 635 (1997)] have been evaluated with the aid of molecular dynamics simulations for a system of particles interacting via a (truncated and shifted) Lennard-Jones potential. This investigation extends earlier results [J. Chem. Phys. 106, 645 (1997)] to spherical interfaces. Further evidence is found that, for the range of curvatures investigated, the surface tension is curvature independent while the investigation of larger curvatures is prevented by the considerable noise found on the liquid side of the interface.

Line of triple points for the hard-core Yukawa model: A computer simulation study

A computer simulation method is devised whereby the change in location of a triple point is followed as one of the parameters of the interaction potential is modified. The method, a two-dimensional Clapeyron integration, is illustrated here for the case of a hard-core plus repulsive Yukawa potential of variable range. The latter is a crude model for charge-stabilized colloids. It is shown that the body-centered-cubic (bcc) phase becomes metastable when the range of the Yukawa term is smaller than, approximately, one-sixth of the hard-core diameter.

Freezing of binary hard-sphere mixtures into disordered crystals: a density functional approach

The density functional theory of freezing is extended to the crystallisation of multicomponent systems into substitutional solid solutions. The formalism is applied to the case of binary mixtures of hard spheres. As the ratio of diameters alpha = sigma 1/ sigma 2 is lowered, the fluid-solid phase diagram evolves from a spindle shape (1> alpha >0.94) into an azeotropic diagram (0.94> alpha >0.92) and finally into a eutectic diagram (0.92> alpha >0.85). The influence of inter-atomic attractions is examined within the van der Waals mean-field approximation. The resulting phase diagrams are even richer than for the bare hard-sphere mixtures, and turn out to be very sensitive to the combination rule for the attractive energy between opposite species.

The freezing of hard disks and hyperspheres

Abstract A unified density functional theory for the freezing of hard rods, disks, spheres and hyperspheres is presented. The hard rod solid is shown to be unstable with respect to density changes (negative compressibility). The results for the hard disk and the hard sphere transition compare well with the computer simulations.

The local pressure in a cylindrical liquid–vapor interface: A simulation study

The equilibrium force distribution, or the local pressure in an interface as defined in a companion paper, has been determined from molecular dynamics simulations of a Lennard-Jones fluid. Both a cylindrical and a planar interface are considered. Limited evidence is found that the surface tension could be independent of the curvature of the interface.

A density functional study of superlattice formation in binary hard-sphere mixtures

A theoretical investigation of a binary mixture of hard spheres confirms that stable superlattice structures, with a complex long-range order of the AB13 type, can form in these simple systems for intermediate values of the diameter ratio, in agreement with recent computer simulations and experimental studies of colloidal suspensions. It is shown that the larger entropy of mixing of the AB13 structure relative to that of the competing structures is responsible for its thermodynamic stability.