Intrinsic spin current for an arbitrary Hamiltonian and scattering potential

We have described electron spin dynamics in the presence of the spin-orbit interaction and disorder using the spin-density matrix method. Exact solution is obtained for an arbitrary two-dimensional spin-orbit Hamiltonian and arbitrary smoothness of the disorder potential. Spin current depends explicitly on the disorder properties, namely the smoothness of the disorder potential, even in the ballistic limit when broadening by scattering is much smaller than the spin-orbit-related splitting of the energy spectrum. In this sense, universal intrinsic spin current does not exist.