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

[Peter Blaha]

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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-- 
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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