[Wannier] Cubefile shift

[Arash Mostofi]

Dear Jiri,

The routine that writes the cube files translates each MLWF centre to 
the home unit cell, defined by the volume of space that has fractional 
crystallographic coordinates in the range [0,1]. But this should always 
shift the position of the centre by an integer number of cell lengths in 
each direction as compared to the MLWF centres that are, for example, 
displayed in the Wannier90 output file at the end of the Wannierisation 
process.

The atomic positions of the system are also written to the cube file. As 
the code is written at the moment, these are not shifted to the home 
unit cell.

In general MLWF centres do not coincide with atomic centres, so it is 
not unusual that they differ by non-integer multiples of the lattice 
vectors.

Hope that helps,

Arash

PS The subroutine that writes cube files is called internal_cube_format 
and can be found in plot.F90 (in the src directory of the W90 distribution).


:------------------------------------------------------------:
: Dr. Arash A. Mostofi           :: a.mostofi at imperial.ac.uk :
: Lecturer and RCUK Fellow       ::                          :
: Depts. of Materials & Physics  ::                          :
: Imperial College London        :: T  +44 (0)207 594 8154   :
: London SW7 2AZ, United Kingdom :: F  +44 (0)207 594 6757   :
:------- http://www.cmth.ph.ic.ac.uk/people/a.mostofi -------:

Jiri Houska wrote:
> Dear all,
> when printing cubefiles using wannier90 and
> 
> wannier_plot=.true.
> wannier_plot_supercell = 2 or 3 (did not matter)
> wannier_plot_format = cube
> 
> , after visualization (VMD) I realized that atomic positions and the  
> orbital positions are obviously shifted (of non-integer times cell  
> size). The shift appears to be different for different MLWFs. Please  
> is is avoidable and/or is there a known reason for that?
> 
> Thanks!
> Jiri Houska
> University of West Bohemia
> 
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