# Spin-orbit in bandstructure

1. Feb 14, 2012

### bahaar

Hi.

I study the bandStructure of SrS with and without Spin-orbit but I have no enough information to explanation it.
the Sr has([kr] 4s2 4p6 5s2) and S has([Ne] 3s2 3p4) Structure. I attache the bandStructure of this compound calculated using pseudopotential(dot-line is with spin-orbit and solid line without Spin-orbit effect).
the lowest band is (4s Sr) the second band is (4p Sr) the , third line is (3s S) and the band below the fermi is (3p s).
I have two question?
1.degeneracy in (4p Sr)band is 3-fold or 6-fold?

2. If the degeneracy for 3band of p like is 3-fold, why we have 3-fold degeneracy in $\Gamma$ point but 2-fold in $X$ point in absent of Spin-orbit? I mean in absent of spin-orbit, what effect splits degeneracy(crystal field)?

3. I don't know how use of H=[1]/[2m2C2r] [dV]/[dr] L.S
to interpret difference in strong splitting between 4p Sr and 3p S?