[Wien] LDA & LSDA Problem

[Kevin Jorissen]

Is it the difference between LDA and LSDA that confuses you?  Option 5 is
BOTH.  Whether or not you have spin polarized calculation depends on the
type of calculation that you do, i.e. :
run_lapw   using 5 in case.in0        is   LDA
runsp_lapw using 5 in case.in0      is  LSDA

You use the same functional in both cases, only for LDA you apply it to the
total density, while for LSDA you apply it for spin up and spin down density
separately.

Hope I didn't misunderstand you,

Kevin.

----- Original Message -----
From: "Sherif Yehia" <wien542002 at yahoo.com>
To: <wien at zeus.theochem.tuwien.ac.at>
Sent: Tuesday, July 15, 2003 6:34 PM
Subject: [Wien] LDA & LSDA Problem


>
> Dear WIEN USER
>
> I am trying to reproduce some of the calculation of a recently published
paper at Phys. Rev.(2003) on SmCo5 compound done by WIEN code The author
mentioned that he used The Local Density approximation (LDA) where he
referred to this reference
>
> J.P. Perdew and Y. Wang Phys. Rev B45 1324 (1996) for
>
> calculating Exc.& Potential in Wienk
>
> I Started by doing init_lapw to do the same calculation, I have the
switches (5 &13& 14)  choosing switch 5 Says LSDA at the interface and in
page 73 in User Guide it  give reference Perdew and  Wang(1992) Phys. Rev
B45 13244 ,reparameterization of C-A data, The recommended LDA option. In
the same time the generated case.in0  says LDA is option 5.
>
> TOT   5     (5...CA-LDA, 13...PBE-GGA, 14...PW2-GGA)
>
> NR2V      (R2V)
>
> ??May be there are some miss understanding in my part and I would
>
> welcome to receive some comments and explanations regarding the
>
> reference used to develop LDA or LSDA and which  of them is implemented
for switch 5  in WIENK.
>
> Thanks all for your time effort and  Patience to answer my  questions
>
> Sherif Yehia
>
>
> Stefaan Cottenier <Stefaan.Cottenier at fys.kuleuven.ac.be> wrote:
>
> > > I am having some problems with the force in my calculation.
> > > I'm working in a supercell with a cluster of 2 Co-atoms near
> substitutional positions in an fcc Ag host (32
> > > atoms in the cell), the calculations are performed for a nonmagnetic
> case, with spin-orbit-coupling.
> >
> > Sorry, but you should not use the forces together with spin-orbit
> coupling.
> >
> > This additional term shouzld also give a term for the forces, which is
> > not implemented.
> >
> > Use forces only without SO.
>
>
> Oops !!? I'm very much surprized, as I don't remember to have heard this
> ever before. A quick check of the UG shows no information on this. Is it
> possible to put a warning in the UG, and/or to let the code stop when one
> tries to use forces with SO? (e.g. scf-cycle refuses to start when -so
> and -fc are used simultaneously, AND lapw2c stops whith an error message
> when -so is used and FOR is detected in case.in2c)
>
> Stefaan
>
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