<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Nicolas,<div><br></div><div>Thank you very much for your reply. I use a Gamma centered 10x10x10 kmesh. </div><div><br></div><div>I'm quite sure that I'm looking at WFs corresponding to top and bottom atoms in the original supercell. If I set "translate_home_cell=.false.", I can clearly see some of the Wannier centers (those close to the lower plane of the cell) are located outside the supercell but they all look pretty normal with "translate_home_cell=.true.". This option however only works for the wannier centers and not for the matrix elements .....</div><div><br></div><div>Anyway thanks again for your help,</div><div>Best,</div><div>Saeed</div><div><br></div><div><br></div><div><br></div><div><br></div><div>On Jun 30, 2011, at 9:41 PM, nicolas poilvert wrote:<div><br class="Apple-interchange-newline"><blockquote type="cite">Dear Saeed,<div><br></div><div>How many k points are you using in the z direction</div><div>of your supercell ? Are you using Gamma sampling</div><div>for the orthogonal directions ?</div><div>Also, the wannier code does not order the wannier</div> <div>functions at all, so make sure that the functions that</div><div>you are looking at are indeed the ones corresponding</div><div>to the proper locations.</div><div>At last, if you use the "translate_home_cell = .true."</div> <div>option, the centers will be translated back to the original</div><div>supercell that you used. Sometimes, some wannier</div><div>functions that are very close to the plane separating</div><div>two adjacent supercells are translated all the way back</div> <div>because of rounding.</div><div><br></div><div>hope this helps,</div><div><br></div><div>best,</div><div><br></div><div>Nicolas<br><br><div class="gmail_quote">On Thu, Jun 30, 2011 at 3:40 AM, Saeed Bahramy <span dir="ltr"><<a href="mailto:bahramy@riken.jp">bahramy@riken.jp</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Dear Wannier90 developers,<br> <br> I have a supercell for which I've been able to make a TB model using<br> wannier functions. The TB model seems to be working fine. However the<br> transfer matrix elements listed in seedname_hr.dat show somewhat<br> unexpected values. Let's suppose my supercell consists of two unit<br> cells along z direction and each cell contains 4 atoms. The relative<br> positioning of atoms is such that atom #1 of cell #1 (let's call it<br> A1) is located near the bottom of supercell and atom #4 of cel #2<br> (let' call it A2) is close to the top of the supercell. In this case,<br> I expect that the transfer matrix elements between A1-A2 to be quite<br> small inside the supercell (rvec= 0 0 0), whereas they should show<br> appreciable values for rvec=0 0 1. However, what I see is totally<br> opposite, i.e., A1-A2 elements are large for rvec=0 0 0 and quite<br> small for rvec = 0 0 0. More strangely, for other two atoms-adjacent<br> to each other and located well inside the first cell- I strangely<br> encounter the situation which I normally expected for A1 and A2. So<br> this basically means that the program shifts all the atoms along z-<br> direction and, hence, assumes a different ordering for atomic<br> positions inside the supercell. I was wondering, if this is a bug or<br> there is an option to turn off such a reordering.<br> <br> Thanking you in advance,<br> <br> -----------------------------------------------------------<br> Saeed Bahramy<br> Correlated Electron Research Group<br> Advanced Science Institute, RIKEN<br> 2-1 Hirosawa, Wako<br> Saitama 351-0198 JAPAN<br> TEL: <a href="tel:%2B81-48-462-1111" value="+81484621111">+81-48-462-1111</a> (EXT. 6013)<br> FAX: <a href="tel:%2B81-48-462-4691" value="+81484624691">+81-48-462-4691</a><br> Email: <a href="mailto:bahramy@riken.jp">bahramy@riken.jp</a><br> -----------------------------------------------------------<br> <br> <br> <br> <br> <br> <br> <br> _______________________________________________<br> Wannier mailing list<br> <a href="mailto:Wannier@quantum-espresso.org">Wannier@quantum-espresso.org</a><br> <a href="http://www.democritos.it/mailman/listinfo/wannier" target="_blank">http://www.democritos.it/mailman/listinfo/wannier</a><br> </blockquote></div><br><br clear="all"><br>-- <br>POILVERT Nicolas<br>PhD candidate,<br>Dpt of Materials Science and Engineering<br>Massachusetts Institute of Technology<br>77, Massachusetts avenue<br>Cambridge, MA 02139<br> USA<br>work: (617) 452-4212<br><a href="mailto:nicolas.poilvert@gmail.com" target="_blank">nicolas.poilvert@gmail.com</a><br> </div></blockquote></div><br></div></body></html>