[Wannier] Phase of plot of wannier functions

[Giovanni Pizzi]

Dear all,

indeed, as Elias says, one has to store a real-valued function in the 
XSF file.

 From plot.F90 in the Wannier distribution:

     ! fix the global phase by setting the wannier to
     ! be real at the point where it has max. modulus

(the lines below this comment have the implementation). Then, in the 
function internal_xsf_format (in the same plot.F90 file), only the real 
part of the functions you get with the 'phase fixing' mentioned above 
are printed to the XSF file.


This should explain the behavior you notice.

Best,
Giovanni



On 12/16/2014 09:54 AM, Elias Assmann wrote:
> On 12/15/2014 07:24 PM, robert.guzman wrote:
>> Do the wannier functions have the correct phase when are plotted with
>> xcrysden?
>
> As far as I know, xcrysden cannot handle complex phases, only positive 
> / negative.  So if your WFs have a true nontrivial phase, xcrysden 
> will not be able to show that.
>
> If it is a “trivial” phase (i.e. they could be made real by a global 
> phase factor), I guess what you will see depends on which interface / 
> plotting program you are using.  Here, I can only speak for 
> wien2wannier: the ‘wplot2xsf’ program uses the sign of the real part 
> [i.e. |w(r)|² * sgn(Re w(r))], which normally works fine.
>
>
> HTH,
>
>     Elias
>
>
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-- 
Giovanni Pizzi
Post-doctoral Research Scientist
EPFL STI IMX THEOS
MXC 340 (Bâtiment MXC)
Station 12
CH-1015 Lausanne (Switzerland)
Phone: +41 21 69 31124