[QE-users] Expectation values of total angular momentum in SOC case

[Lorenzo Paulatto]

>     Yet, the DFT expectation values for Sx, Sy,
>     Sz do not result in a spin of 1/2 (for the TMD heterostructure) but a little
>     bit less, 0.468, and this value is too different from 1/2 to say it is
>     numerical noise. 

I'm not an expert in this subject, but I see it like this: you want to 
isolate a quasi-particle band, which is more or less equivalent that 
getting its Wannier function.  When doing a non-collinear calculation, 
Wannier functions are spinors.

It could be possible, for your case, to compute this Wannier function 
and see if its spin angle turns out to be constant, e.g. because of 
symmetry reason or dimensionality. (See Wannier90 example 17 or 18)

cheers



-- 
Lorenzo Paulatto - Paris