which does not apply when l=0l=0 (as it would be singular). ll is the orbital angular momentum of the electron, ss is its spin angular momentum, and jj is the total angular momentum given by |l−s|≤j≤l+s|l−s|≤j≤l+s in integer steps (j=l+s)(j=l+s).
For the example of hydrogen in the n=2n=2 level:
Am I right in thinking there is not supposed to be any shift for the l=0l=0 s-orbital (j=12j=12)? We can't calculate anything using the formula above in this case, but for the