[Wien] Unknown magnetic ground state

[Laurence Marks]

The general answer is the in KS there is no reason why one cannot have more
than one local minimum, Hence depending upon the starting point, you may
find a different minimum in both positions, magnetic state etc. The
rigorous way is to try different initial states, in some cases use
runfsm_lapw for some cycles first including optimization and see.

In some cases I have seen magnetic states switch during optimization to the
global minimum, but nothing in KS or the mixer dictates that this will
always happen.

On Wed, Nov 5, 2014 at 10:04 AM, Alexander Alexander <
alexanderwien2k at gmail.com> wrote:

>     Dear all,
>
>  I want to indicate the magnetic ground state of a bulk crystal which is
> not known experimentally, I know I have to set up different magnetic
> ordering which might be many Antiferromagnetic orderings(AF1, AF2, AF3,
> ...) and one Ferro ..., and in the end just comparing their SCF energy to
> find the lowest one.
> My first question is:
> Should the orders in a specific ordering for example AF2, must be fixed?
> if not, do not you think that all different orderings converge finally to
> the same state? as these orders we indicate in the beginning are just a
> initial ordering and they are probably allowed to change as SCF approaches
> to the convergence.
>
>  The second question is:
>  I was wondering if different orders (AF1, AF2, ... , Ferro ...), must be
> optimized and minimized first? and then run the usual SCF for every of
> them. Because as I know the magnetic state is a effective parameter on the
> final optimized structure. If the per-optimized is not that necessary, then
> which structure must be considered as platform to setup different magnetic
> ordering on it, maybe optimized one none-magnetically.
>
>  I hope I could clearly asked my question and any comment would be highly
> appreciated.
>
>  Best regards,
>
>  Alex
>



-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu
Corrosion in 4D: MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
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