GROWTH OF HEXAGONAL STRING PHASES IN SHEARED COLLOID SIMULATION

Strongly sheared colloids often form strings oriented along the shear direction, which in turn often order into a quasi-2D hexagonal lattice . We examine this ordering process in detail to elucidate its strong s ystem-size dependence, which is a major obstacle to establishing a con nection between simulation and experiment. We catalog the possible lat tices and use an energy criterion to predict which one a particular sy stem is likely to crystallize in. The process is similar to nucleation and growth in a true 2D system except that strings crystallize withou t point defects (vacancies and interstitials), unlike 2D disks, becaus e particle (string) number is not conserved.