Brownian dynamics simulations of Laponite colloid suspensions

Abstract

Colloidal suspensions of Laponite clay platelets are studied by means of Brownian dynamics simulations. The platelets carry discrete charged sites which interact via a Yukawa potential. As in the paper by S. Kutter et al. [J. Chem. Phys. 112, 311 (2000)], two models are considered. In the first one all surface sites are identically negative charged, whereas in the second one, rim charges of opposite sign are included. These models mimic the behavior of the Laponite particles in different media. They are employed in a series of simulations for different Laponite concentrations and for two values of the Debye length. For the equilibrium states, the system structure is studied by center-to-center and orientational pair distribution functions. Long-time translational and rotational self-diffusion coefficients are computed by two different methods, which yield very similar results.

Hard ellipsoids: Analytically approaching the exact overlap distance

“…Almost forty years later, with the huge advance of computing power, the development of very efficient and easy to use software based on the so called force-fields, and the possibility of simulating a complete and solvated protein by handling several thousands of atoms, one is tempted to think that these lines are obsolete. Notwithstanding, there is nowadays a great effort on developing and studying pair potentials which goes in the coarse-grained direction [11][12][13][14][15]. In fact, ellipsoids are frequently used as models for highly anisotropic and relatively rigid supramolecular structures, such as biological membranes, DNA-phospholipidic complexes, and other anisotropic entities like nanotubes, inorganic nanorods, clay crystals, among a wide variety of colloidal particles.…”

Aging in a Laponite colloidal suspension: A Brownian dynamics simulation study

“…A Brownian dynamics simulation has been presented in Ref. [30], with a focus on structure and dynamics at equilibrium. Here we present an analysis of the out-of-equilibrium dynamics of a model introduced in Ref.…”

Relaxation dynamics in the columnar liquid crystal phase of hard platelets

“…Therefore, we make use of the analytical expressions proposed for oblate ellipsoids, 93,94 which were more recently applied to investigate the Brownian dynamics of colloidal suspensions of Laponite clay platelets. 95 We argue that possible deviations given by the difference in shape of the two discotic particles are negligible, such that the ratio between the short-time diffusion coefficients reads…”