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

[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