Viscosities of liquid metal alloys from nonequilibrium molecular dynamics

We have developed a nonequilibrium molecular dynamics (NEMD) approach to predict viscosity by including external shear rates directly into the Hamiltonian equations of motion. Using the quantum Sutton–Chen (Q–SC) many-body potentials for Au and Cu, we applied NEMD to predict the viscosity as a function of shear rates for Au_xCu_(1−x) alloys with x ranging from 0 to 100%. This was done for temperatures of 1500 K to 2000 K. The predicted viscosities are in reasonable agreement with experiment. In particular, we find that fixing the density and changing the temperature leads to very little change in the shear viscosity. Thus, the temperature dependence in viscosity is mainly due to the change in density with temperature.