[Wannier] hidden actions taken by wannier90?

[jon]

Dear Prof. Marzari,

Let me see whether I interpret your paper right. Basically, for a crystal
with lower symmetry, MLWS could still have arbitrariness in choosing its
form. Thus, introducing a new criterion by minimizing <r^2> could further
reduce the arbitrariness, but not fully remove it. So, is this what you mean
by "to recover symmetries that are not built in in the second-moment
minimization"?

I guess the then relevant question related to my problem would be: is
minimization on <r^2> implemented in the wannier90 code? To help understand
the issue better, I would ask two more questions: is this minimization
equivalent to attempts to build in lattice symmetry further, or in other
words, is the removal of arbitrariness equivalent in some sense to
restoration of crystal symmetry for the wannier states? Is there logic
behind if this equivalence holds?

Thanks for your kind help,

Sincerely,
Jon

On Thu, May 7, 2009 at 12:30 PM, Nicola Marzari <marzari at mit.edu> wrote:

> Nicola Marzari wrote:
>
>>
>>
>> Dear Jon,
>>
>>
>> have a look at the Posternak...Marzari 2002 PRB. I presume that
>> that refers to your problem - you need to diagonalize in the subspace of
>> localized orbitals to recover symmetries that are not built in in
>> the second-moment minimization.
>>
>> Let us know if that is the problem that affects you,
>>
>>            nicola
>>
>>
>> jon wrote:
>>
>>> Dear Colleagues,
>>>
>>> I am working on DMFT applied to iron pnictide and need to obtain the
>>> impurity Green function, which is basically the bare Green function being
>>> summed over all the momentum points in 1BZ. The tight-binding hoppings are
>>> extracted from fitting to a band structure calculated through MLWS using
>>> wannier90. These hoppings have cubic symmetry(on 2D plane though). The
>>> impurity Green function turns out to be diagonal in the orbital indices.
>>> This is not generally the case unless the wannier states have been taken
>>> further actions to form cubic harmonics(I am not an LDA expert, thus please
>>> correct me if I am wrong here) before output. However, the tutorial or
>>> introduction does not explicitly mention this action and I am thus confused.
>>>
>>> Thanks,
>>>
>>> Sincerely,
>>> Jon
>>>
>>>
>>> ------------------------------------------------------------------------
>>>
>>> _______________________________________________
>>> Wannier mailing list
>>> Wannier at quantum-espresso.org
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>>>
>>
>>
>>
>
> --
> ---------------------------------------------------------------------
> Prof Nicola Marzari   Department of Materials Science and Engineering
> 13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
> tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu
>
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