[Wannier] Reduced unit cell issues

[Nicola Marzari]

Lex Kemper wrote:
> Hey everyone,
> 
> I'm attempting to calculate the Fermi surface / wannier band structure 
> for a body-centered tetragonal system. The bct system is the primitive 
> unit cell for one that I've calculated before, which is tetragonal (a =b 
> < c). The tetragonal system finishes fine -- I end up with a real 
> Hamiltonian. When I try the bct system, it always ends up complex. Any 
> suggestions?


Dear Lex,

of course the first thing to check out would be the WFs themselves -
are those real ? If they are not, I presume the code gots stuck
in a false minima, and you should use the initial projections as
a hint for the WFs procedure (given also that you have a good sense
from the tetragonal calculations, of what the WFs look like).

If you are using projections, and the WFs end up being complex,
it might point out to a mismatch in what you and the code think
abut the projection centers in absolute/relative coordinates.

				nicola

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Prof Nicola Marzari   Department of Materials Science and Engineering
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