Viscosity of finite Yukawa liquids

The shear viscosity of a finite two-dimensional (2D) Yukawa liquid is calculated using non-equilibrium Langevin simulations. Two counter-propagating shear forces are used to push the particles and cause shear-induced melting of the cluster. The melting temperature of the 2D cluster system is used to derive the effective coupling parameter G* of this finite system and allows us to investigate the relationship between shear viscosity and system properties G * and ?. The simulation data shows that the value of the shear viscosity rises for coupling parameters G * > 20 and follows a simple universal scaling for appropriate normalization. It is further found that the Green-Kubo relation is applicable to determine viscosity in finite non-equilibrium systems with G * < 80.