Terms and Variables in SG SWEP
•In general,  VNN(x) = VC + VT+ VLS + VLL
* The significance of  the LS term, specially for odd triplet states was known  as early as 1957. P. Signell and R. Marshk, Phys Rev. 106 ,837 (1957); Phys Rev. Lett 109,1229 (1958)