RHEOLOGY, SELF-DIFFUSION, AND MICROSTRUCTURE OF CHARGED COLLOIDS UNDER SIMPLE SHEAR BY MASSIVELY-PARALLEL NONEQUILIBRIUM BROWNIAN DYNAMICS

The simple shearing of a suspension of charge-stabilized, colloidal pa rticles close to the melting line is investigated by massively paralle l, nonequilibrium Brownian dynamics (NEBD) simulation. The suspension undergoes a discontinuous transition from a distorted fluid structure to an ordered ''string'' phase. Comparisons between simulations of 43 000, 4725 particles, and previous NEED work on less than or equal to 5 00 particles proves that shear-induced ordering is not all artifact of the small system sizes. We also show that the shear-rate dependence o f the rheological properties obtained from NEED is different than thos e obtained from nonequilibrium molecular dynamics (NEMD), a consequenc e of the solvent damping not being present in NEMD. The validity of th e Ree-Eyring model for viscosity and the stress-optic law for colloids are tested. Further, a type of generalized Stokes-Einstein relationsh ip is discovered for systems under shear. (C) 1996 American Institute of Physics.