PROFILE UNBIASED THERMOSTAT WITH DYNAMICAL STREAMING VELOCITIES

We have devised a reversible set of nonequilibrium molecular dynamics equations of motion to study viscous flow under an applied shear field utilizing a new profile unbiased thermostat: (PUT). Based on a modifi cation of the original equations presented by Evans and Morriss [Phys. Rev. Lett. 56, 2172 (1986)], we have extended the phase space to incl ude dynamically evolving streaming velocities. The new method is advan tageous because it allows control of the rate at which the streaming v elocities evolve and thereby removes the effects of high frequency the rmal fluctuations. Further, in tests on a Weeks-Chandler-Andersen flui d, we find that a shear-induced microstructure, the so-called ''string phase,'' was not destabilized by the new PUT scheme. (C) 1996 America n Institute of Physics.