We study the structure of numerically simulated hard sphere packings at different densities by investigating local tetrahedral configurations of the spheres. Clusters of tetrahedra adjacent by faces present relatively dense aggregates of spheres atypical for crystals. The number of spheres participating in such polytetrahedral configurations increases with densification of the packing, and at t...

HARD, SOFT, AND STICKY SPHERES FOR DYNAMICAL STUDIES OF DISORDERED COLLOIDAL PACKINGS Matthew Daniel Gratale Arjun G. Yodh This thesis describes experiments which explore the role of interparticle interactions as a means to alter, and control, the properties of dense colloidal packings. The first set of experiments studied phonon modes in two-dimensional colloidal crystals composed of soft micr...

We present new results for the virial coefficients Bk with k ≤ 10 for hard spheres in dimensions D = 2, · · · , 8.

We examine several variational methods for determining bounds on the free energy of model crystalline phases, as applied to hard spheres in one and three dimensions. Celland harmonic-based reference systems are considered. Methods that provide the tightest bounds on the free energy are similar in form to free-energy perturbation, and are prone to inaccuracy from inadequate sampling. Gibbs–Bogol...

Crystallization and vitrification are two different routes to form a solid. Normally these two processes suppress each other, with the glass transition preventing crystallization at high density (or low temperature). This is even true for systems of colloidal hard spheres, which are commonly used as building blocks for novel functional materials with potential applications, e.g. photonic crysta...

We study the demixing transition of mixtures of equal size hard spheres and dipolar hard spheres using computer simulation and integral equation theories. Calculations are carried out at constant pressure, and it is found that there is a strong correlation between the total density and the composition. The critical temperature and the critical total density are found to increase with pressure. ...

Mixture of flexible polyions with 120 monomer units, equivalent number of oppositely charged counterions and solvent molecules, represented by hard spheres with four square-well off-center sites, was studied by an extension of the product-reactant Ornstein–Zernike theory. Polyions were represented as freely jointed chains of charged hard spheres, and all the species were embedded in continuous ...

Experiments, theory, and simulation were used to study glass formation in a simple model system composed of hard spheres with short-range attraction ("sticky hard spheres"). The experiments, using well-characterized colloids, revealed a reentrant glass transition line. Mode-coupling theory calculations and molecular dynamics simulations suggest that the reentrance is due to the existence of two...