Finally, it should be pointed out that symmetry-breaking con-tributions in the Hamiltonian of the real system necessarily lead to corresponding terms in the Kohn-Sham Hamiltonian. Spinorbit interactions, for example, require from a formal point of view the presence of terms in the Kohn-Sham potentials that couple to spin or magnetization currents. In practice, these terms are often neglected. It is interesting to note that, from a formal point of view, terms in the Kohn-Sham potential that couple to noncollinear spin are not required in the presence of spin-orbit interactions. 410 (3.6.10) Chermette :