Hey Lorenzo,
There are definitely regions in the BZ where the spin is restricted to
certain directions but away from these high-symmetry points (or lines)
it is pointing in different directions. For example at the K point it
needs to point in the z direction. And I see this in the results -
expectation values of Sx and Sy are zero and Sz is 0.47. But 0.47 for an
s=1/2 particle? This is what I don't understand but which might be due
to SOC (I thought)... But then, why it is like this in a TMD
heterostructure but not in HfNCl (same BZ) where I see 0.499?
Thomas
On 1/23/20 4:25 PM, Lorenzo Paulatto wrote:
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
--
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig
Tel: +49 (0)341 97 36456
email: [email protected]
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