[Wannier] Too many projections defined error

[Arash A Mostofi]

Dear Brad

I think the problem is in the "projections" block of the input file, not 
the energy windows. As you say, a 12 atom unit cell of silicon will need 24 
maximally localised Wannier functions (MLWFs) to span the valence manifold 
and this is the number of projections you should define in the projections 
block.

What we've found is that the generation of MLWFs for the valence manifold 
is very robust to the initial guess, so even specifying randomly centred 
s-orbital projections is good enough. This can be done by setting

Begin Projections
random
End Projections

in the input file.

Cheers

Arash

-----------------------------------------
Dr Arash A Mostofi
Dept of Materials Science and Engineering
13-4084 MIT
77 Massachusetts Avenue
Cambridge MA 02139-4307 USA
Tel: 617.2536026
-----------------------------------------

On Fri, 25 May 2007, Brad Malone wrote:

> Hi, I'm having an issue that I'm very confused about.  I'm running a
> calculation on silicon with 12 atoms per unit cell.  There is a gap in my
> system (pwSCF tells me that 7.3 is the highest occupied state and 8.4 is the
> lowest unoccupied state).  I just care about the valence bands and so I set
> my upper energy window to 7.8 eV and set num_wann=24 (num_bands=32).  My
> frozen energy window is the same as my larger window and it covers all 24
> valence bands.  However, when I run the wannier code to generate the .nnkp
> file it tells me the following error:
>
> param_get_projection: too many projections defined
>
>
>
> Any help in understanding why this is would be greatly appreciated!
>
> Best,
> Brad
>