[Wien] Questions in "initso_lapw" when using "runsp_c_lapw" to run my task

[Fecher, Gerhard]

Another "misuse" of U might be to shift the binding energies of the Lu 4f electrons in "nonmagnetic" compounds
without U the Lu 4f doublet appears, roughly speeking, centered at about -5eV, with a moderate U of 0.5 Ry one can shift it to the value found in photoelectron spectroscopy at about -9eV. 
(and, indeed, the calculation is spin polarized, it is in that case , however, already enough to set the initial spin polarisation to zero with instgen_lapw).

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von Peter Blaha [pblaha at theochem.tuwien.ac.at]
Gesendet: Dienstag, 11. Juli 2017 08:38
An: wien at zeus.theochem.tuwien.ac.at
Betreff: Re: [Wien] Questions in "initso_lapw" when using "runsp_c_lapw" to run my task

Some people use (or misuse ?) U also in nonmagnetic systems (band gap of
ZnO with a huge Zn-3d U).

In any case, as mentioned before, you have to use a spin-polarized setup
for LDA+U and if you want to restrict to zero magnetization (and save
time) you can use   runsp_c_lapw -orb [-so].

 From the symmetry point of view, however, this is a spin-polarized
calculation and thus when spin-orbit is included, you have to answer
"spin-polarization yes" during initso. This will (in many cases) reduce
the symmetry.

Am 11.07.2017 um 05:34 schrieb Gavin Abo:
>
>> A Hubbard U does not make much sense in a non spin polarized
>> calculation - and I seem to recall that this is mentioned in the UG.
>
> Perhaps thinking of run_lapw?
>
> username at usernamecomputer:~/Desktop$ run_lapw -h | grep orb
> hup: Command not found.
> -so   ->    run SCF including spin-orbit coupling
>
> Unlike run_lapw, runsp_c_lapw seems to have this option [1,2]:
>
> username at usernamecomputer:~/Desktop$ runsp_c_lapw -h | grep orb
> hup: Command not found.
> -so   ->    run SCF including spin-orbit coupling
> -dm   ->    calculate the density matrix (when -so is set, but -orb is not)
> -orb  ->        use LDA+U, OP or B-ext correction
> -orbc ->        use LDA+U correction, but with constant V-matrix
> -noorbud ->     use LDA+U without crossterms up-dn (needs also -so)
>
>> initso_lapw is, on the other hand, for spin-orbit interaction - there
>> the question if you have a spin polarized case makes sense. This is
>> also explained in the UG.
>
> I agree, if not using the -so option ("runsp_c_lapw -so" or
> "runsp_c_lapw -so -orb"), it doesn't seem to make sense to use initso
> with runsp_c_lapw -orb.
>
>>> My purpose is to use LDA+U to treat no-magnetic system. So I use
>>> "runsp_c_lapw -orb" to run my task, as told by the user_guide. And in
>>> "initso_lapw", it asks me "do you have a spinpolarized case ?" and "do
>>> you want to use the new structure for SO calculations ?". I answer
>>> "Yes" to both the two quetions. I'm not very sure whether what I do is
>>> right. I'd like to listen your experience and advices about this.
>
> In the WIEN2k 17.1 usersguide [3] on page 48 in section "4.5.6 Orbital
> potentials", it says:
>
> If you want to force a non-magnetic solution you can constrain the
> spin-polarization to zero using runsp_c _lapw.
>
> I'm not an expert on such a calculation, but I think that implies that
> you would want to answer No in initso to "do you have a spinpolarized
> case ?" or to "do
> you want to use the new structure for SO calculations ?" to force a
> non-magnetic calculation.  My current understanding is that answering
> Yes to both of those questions changes the symmetry.
>
> And, I think it has been said that non-magnetic systems should not lead
> to changing of the symmetry [4]:
>
> In non-magnetic systems, the inclusion of the spin-orbit coupling does
> not lead to lowering of the symmetry.
>
> [1]
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg07023.html
> [2]
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg00318.html
> [3] http://susi.theochem.tuwien.ac.at/reg_user/textbooks/usersguide.pdf
> [4]
> http://susi.theochem.tuwien.ac.at/reg_user/textbooks/novak_lecture_on_spinorbit.pdf
>
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