Incorporating friction and collective shear moves into a lattice gas.

Here we examine a lattice-gas model that has been extended to include collective shear moves and friction interactions between particles. A shearlike field is applied by periodically translating entire subsections of the lattice with respect to one another, as opposed to biasing the individual movements of particles. Friction is introduced by forming a network of temporary bonds between particles that prevent particles from moving along with the flow. The extent of the network is controlled by the sticking parameter, P stk. We find that there are two distinct phases in the model: an isotropic phase that exhibits only small fluctuations in local density, and a striped phase that features one or more large clusters of particles that span the system. We examine the transition between these two phases using the radial distribution function. By introducing a measure of viscosity, we examine the relationship between the viscosity and shear rate for many different densities and values of P stk, and pursue an analogy to colloidal shear-thickening systems.