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

[Saeed Bahramy]

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,

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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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