BROWNIAN DYNAMICS SIMULATIONS OF COLLOIDAL HARD-SPHERES - EFFECTS OF SAMPLE DIMENSIONALITY OF SELF-DIFFUSION

The self-diffusion coefficients of colloidal hard spheres were determi ned by Brownian dynamics (BD) computer simulations using a new efficie nt algorithm for treatment of the hard-sphere interactions. Calculatio ns were done on an Apple PC type MacIIcx and on a MicroVAX 3000, consi dering samples in two and three dimensions at varying particle concent rations. Our results in three dimensions are compared with experimenta l results from our own group which were obtained by forced Rayleigh sc attering (FRS), and with numerical results from a dynamical Monte Carl o simulation by Cichocki and Hinsen. Good agreement with 'the latter w as found for particle volume fractions up to 0.40. Differences in the dynamical behavior of our numerically treated 2D and 3D samples are di scussed using a simple geometrical model to enable comparison of parti cle concentrations in samples with different dimensionality.