Energy landscapes and the non-Newtonian viscosity of liquids and glasses.

An inherent structure analysis of viscosity is developed based on results of nonequilibrium molecular dynamics simulations. The viscosity is separated into a "structural" contribution associated with the energy minima that the system visits, and a "vibrational" contribution associated with displacements within the energy minima. The structural contribution is shear thinning due to strain-activated relaxations caused by the disappearance of high-stress energy minima, while the vibrational contribution is Newtonian.