I am trying to simulate viscosity of water including a silver nanoparticle with diameter of 2nm and volume fraction of 2%. To do this I used GK formalism as stated in LAMMPS example folder ( calculating the auto-correlation of pxy). But I found the viscosity of the system same as pure water. Is GK a appropriate method to calculate the viscosity of this non-homogenous system? Does “compute pxy” give the true shear viscosity of this non-homogenous system?