OK, I retract the question... It is really dumb. One just has to think a
bit about what "expectation value" really means.
Anyways, cheerio
Thomas
On 7/7/22 15:03, Thomas Brumme wrote:
Dear all,
I'm calculating the full-relativistic band structure of some WSe2
nanotubes which works fine and also the band structure agrees with
calculations done with FHI-aims (which I have to use for larger systems).
In order to understand some interesting feature in the band splitting
I'm also calculating the expectation values of the spin operators
using bands.x and setting lsigma(1..3) to .true.
Yet, for some of the bands all expectation values are zero. I don't
understand this. OK, I know that only the total angular momentum is
conserved and spin is not a good quantum number anymore but does this
also mean that the expectation value for the "spin vector" can be
zero? I had a similar problem in the past for a monolayer WSe2 and
there the spin was also not really 1/2 anymore which might actually be
a DFT-specific problem as far as I understood it after discussing with
other colleagues. But zero?
Kind regards
Thomas Brumme
--
Dr. rer. nat. Thomas Brumme
Theoretical chemistry
TU Dresden - KOE / 103
Bergstr. 66c
01069 Dresden
Tel: +49 (0)351 463 40844
email: [email protected]
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