[Wannier] kpoint

[Jonathan Yates]

On Jun 25 2008, Vivek Ranjan wrote:


>I have successfully run scf and nscf calculations using pwscf. In the next
>stage - wannier code to get generate overlaps - I input the same kpoints
>as automatically generated in scf steps (in units of 2*pi/a). But wannier
>stops making a complaint :
>
>Exiting.......
>Non-symmetric k-point neighbours!
>
>I cannot understand the reason. Can someone help in what could be wrong ?

Vivek,

Wannier90 expects the kpoints to form a regular grid. Conventionally this 
would be a regular grid in the reciprocal unit cell (as generated by the 
script utility/kmesh.pl)
 Note that W90 does not (at present) take account of any symmetry - ie you 
must give the kpoints in the full zone (not the symmetry reduced kpoints)

 The error message simply means that W90 thinks your kpoints do not form a 
regular grid. A few possibilities: you are using the symmetry reduced 
kpoints from the scf, you have not specified the kpoints to enough decimal 
places (eg for a 6 6 6 mesh). I suggest using the kmesh.pl script to 
generate the kpoints for W90 and nscf calculations.

 If none of these suggestions help, please post your input files (without 
them we can only guess at the problem)

 Jonathan

--
Cavendish Lab, Cambridge, UK