[Wannier] working in IBZ only

[Nicola Marzari]

Dear Julien,


first of all, let's consider the orbital-independent case.

It doesn't, sadly, without some modifications of the code. I think these 
shouldn't
be really difficult, but I suspect they would belong more to pwscf 
rather than
Wannier (hence the crosspost) - i.e. one could have in pwscf an option 
that for the nscf step
calculates the u_nk at the k-points in the IBZ, and outside that they 
are generated
by symmetry operations rather than diagonalization.

A shortcut that you might be able to implement yourself in pw2wannier 
(unless
it's already there) is that you could only calculate in pw nscf the u_nk 
on half the BZ,
and then reconstruct the u_nk in the other half.

For the orbital-dependent case, everything breaks down in the most general
case (you have a different Hamiltonian for every orbital). But I suppose 
that if you
have Hartree-Fock, or a mix of Hartree-Fock and GGA, you would still be ok
in principle (Hartree-Fock codes, like Crystal, do exploit symmetry), 
but I'm not
really sure on how complex that is to implement in the pw exx part (that 
I do not
know).

             nicola




Julien Vidal wrote:
> Dear all
>
> I have a question about the possible use of symmetries in wannier90. I
> want to calculate the wannier functions starting from PBE0 output from PW.
> However, the non self-consistent run step described in some tutorial
> examples in order to generate wave functions on a uniform grid of k points
> in the whole Brillouin zone is computationally intensive when using
> orbital dependent functionals. I was wondering if you can use the output
> from the self-consistent PBE0 run on a set of k points restricted to the
> irreducible Brillouin zone and then run Wannier90 (i.e. bypass the non
> self consistent run step)
>
> I guess it may be feasible as it works with abinit but I dont know if it
> is the same for PW.
>
> thank you in advance
>
> Julien Vidal
>
> _______________________________________________
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> Wannier at quantum-espresso.org
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>   


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Prof Nicola Marzari   Department of Materials Science and Engineering
13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
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