[Wannier] Question about the matrix elements in seedname_hr.dat

[nicolas poilvert]

Dear Saeed,

How many k points are you using in the z direction
of your supercell ? Are you using Gamma sampling
for the orthogonal directions ?
Also, the wannier code does not order the wannier
functions at all, so make sure that the functions that
you are looking at are indeed the ones corresponding
to the proper locations.
At last, if you use the "translate_home_cell = .true."
option, the centers will be translated back to the original
supercell that you used. Sometimes, some wannier
functions that are very close to the plane separating
two adjacent supercells are translated all the way back
because of rounding.

hope this helps,

best,

Nicolas

On Thu, Jun 30, 2011 at 3:40 AM, Saeed Bahramy <bahramy at riken.jp> wrote:

> Dear Wannier90 developers,
>
> I have a supercell for which I've been able to make a TB model using
> wannier functions. The TB model seems to be working  fine. However the
> transfer matrix elements listed in seedname_hr.dat show somewhat
> unexpected values. Let's suppose my supercell consists of two unit
> cells along z direction and each cell contains 4 atoms. The relative
> positioning of atoms is such that atom #1 of cell #1 (let's call it
> A1) is located near the bottom of supercell and atom #4 of cel #2
> (let' call it A2) is close to the top of the supercell. In this case,
> I expect that the transfer matrix elements between A1-A2  to be quite
> small inside the supercell   (rvec= 0 0 0), whereas they should show
> appreciable values for rvec=0 0 1. However, what I see is totally
> opposite, i.e., A1-A2 elements are large for rvec=0 0 0 and quite
> small for rvec = 0 0 0. More strangely, for other two  atoms-adjacent
> to each other and  located well inside the first cell- I strangely
> encounter the situation which I normally expected for A1 and A2. So
> this basically means that the program shifts all the atoms along z-
> direction and, hence, assumes a different ordering for atomic
> positions inside the supercell. I was wondering, if this is a bug or
> there is an option to turn off such a reordering.
>
> Thanking you in advance,
>
> -----------------------------------------------------------
> Saeed Bahramy
> Correlated Electron Research Group
> Advanced Science Institute, RIKEN
> 2-1 Hirosawa, Wako
> Saitama 351-0198 JAPAN
> TEL: +81-48-462-1111 (EXT. 6013)
> FAX: +81-48-462-4691
> Email: bahramy at riken.jp
> -----------------------------------------------------------
>
>
>
>
>
>
>
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-- 
POILVERT Nicolas
PhD candidate,
Dpt of Materials Science and Engineering
Massachusetts Institute of Technology
77, Massachusetts avenue
Cambridge, MA 02139
USA
work: (617) 452-4212
nicolas.poilvert at gmail.com
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