[Wannier] Re: Too many projections defined error

[Brad Malone]

Thanks for the response Arash.  Setting the projections to random (they were
set to sp3) did indeed fix that issue.  I ran the wannier code and generated
the .nnkp file.  However, in the nnkp file it lists my excluded bands as
being 25-32 (which I had specified in the .win input file; perhaps
unnecessary because my window excludes them anyway) but also it lists band
#8 as being excluded, and I did not want or specify that.  Is there a reason
for this?  I'm worried that it may be causing me an error when I run the
Wannier code again because I get an error of "param_read: mismatch in
silicon.eig".  Inspecting the silicon.eig file it looks like it should be
okay, unless the code thinks that there are 23 bands (having excluded band
8), as there are 24 bands (for my 64 points) listed in the silicon.eig file.

I'm also interested in the bottom of the conduction band.  Do you have a
feel for how robust this is to the initial guess for the projections?  And
is it possible for me to specify sp3 projections without having 48 wannier
bands?  I'd like to use fewer bands if possible because it seems that I'm
running into memory allocation issues that prevent me from starting with a
denser k-grid. Thanks again for the help.

Brad



> Message: 1
> Date: Fri, 25 May 2007 12:58:31 -0700
> From: "Brad Malone" <brad.malone at gmail.com>
> To: wannier at quantum-espresso.org
> Subject: [Wannier] Too many projections defined error
>
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> 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
>
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> 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:
> <br><br><blockquote style="border-left: 1px solid rgb(204, 204, 204);
> margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"
> class="gmail_quote"> param_get_projection: too many projections
> defined</blockquote><div><br><br>Any help in understanding why this is would
> be greatly appreciated!
> <br><br>Best,<br>Brad<br></div><br><br>
>
> ------=_Part_139432_23760487.1180123111998--
>
> --__--__--
>
> Message: 2
> Date: Fri, 25 May 2007 16:22:28 -0400 (EDT)
> From: Arash A Mostofi <mostofi at MIT.EDU>
> To: Wannier List <wannier at quantum-espresso.org>
> Subject: Re: [Wannier] Too many projections defined error
>
> 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
> -----------------------------------------
>
>
>
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