[Wien] state normalization problem violates correct spin expectation value :: modified w2w code

[Peter Blaha]

I don't know the w2w code, but a possible guess is that it restricts 
itself inside the sphere to some lower lmax value ??? and thus cuts off 
some contributions of higher l.



On 02/23/2017 10:14 AM, Martin Gmitra wrote:
> Dear Wien2k users,
>
> I have modified w2w code to calculate overlaps and consequently spin
> expectation values for states of interest.
>
> For the tests I consider an artificial system -- a flat germanene with
> spin-orbit coupling without RLO. The system has inversion and thus all
> the states are spin degenerated. Spin-expectation values are obtained
> by diagonalizing (rotating) a generalized spin matrix. As the spin
> should follow certain symmetry constrains I have observed tiny
> violations.
>
> Further inspection of the violations points to the normalization of
> the states that shows that the states are not perfectly
> othonormalnormali. For instance the overlaps for a degenerate band (n)
> close to Fermi level at the K point are:
>
> <n, K | n, K> = 0.999990071859
> <n+1, G| n, G> = 0.0
> <n+1, K | n+1, K> = 0.999990071859
>
> The w2w code works only with spherical potential. Looking into lapwso,
> non-spherical contributions to the Hamiltonian are added only if RLO
> is included in vnsrint.F. Therefore I suggest that the non-spherical
> contribution should not matter in my case once diagonalization of the
> Hamiltonian in lapwso should provide orthonormal states.
>
> My question is -- do you have any hints what could be missing to get
> perfectly normalized state?
>
> Best regards,
> Martin Gmitra
> Uni Regensburg
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>

-- 

                                       P.Blaha
--------------------------------------------------------------------------
Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
WWW:   http://www.imc.tuwien.ac.at/TC_Blaha
--------------------------------------------------------------------------