Nonequilibrium phase diagram of a polydisperse system: A molecular dynamics study

We investigate the structural changes of a polydisperse system undergoing a n oscillator shear flow by use of a nonequilibrium molecular dynamics simul ation. The nonequilibrium phase diagrams are investigated in the space of t he amplitude of the shear rate and the number density at several polydisper sities. At small polydispersity, phase changes to two types of layered stru ctures are observed and this phenomenon is similar to that in the monodispe rse case. With increase of polydispersity, the system becomes disordered, a nd an amorphous phase is observed in the equilibrium state. Furthermore, we investigate the size dependence of structural changes in the polydisperse system. In consequence, we observe less of a dependence on the phase change s in our oscillatory shear case. (C) 2000 American Institute of Physics. [S 0021-9606(00)50224-4].