Local and global order in a simulated two-dimensional liquid under steady shear.

Abstract

The dependence of ``stringlike'' order on system size in nonequilibrium molecular dynamics simulations of a two-dimensional liquid of soft disks under steady shear is reported. Local order, as measured by the calculated Bragg intensities from a fixed scattering volume, is found to be independent of the simulation box length. The global ordering of the ``strings,'' however, is observed to decrease steadily with increasing cell length along the flow direction. This is a consequence of the increase in the number of uncorrelated domains as the system becomes larger. The implications of the (probable) disappearance of global order in the thermodynamic limit for the discussion concerning choice of thermostat is considered. It is suggested that the domains of shear-induced order may arise from the large structural fluctuations at equilibrium. \textcopyright{} 1996 The American Physical Society.