[Wannier] h(r) hoppings in AO basis

Ganesh Panchapakesan gpanchap at gmail.com
Fri Jan 25 19:37:49 CET 2013


Thanks.  Yes, I later realized that with zero localization step the
(U(dis)(k))^dagg.H(k).U(dis)(k)  essentially projects the bloch-states onto
the trial basis within the chosen energy window (and also diagonalises the
H in that subspace by construction), which as you mention can include
unoccupied bands as well.  This is what I needed.


On Fri, Jan 25, 2013 at 12:07 PM, David Vanderbilt
<dhv at physics.rutgers.edu>wrote:

> Ganesh,
> Regarding this part
>  Does anyone know if it is possible to transform the current
>> h(r) matrix elements, which is in the WF-basis, to (say
>> an atom centered) atomic-orbital basis within wannier90?
>> The transformation might be lossy (i.e. it might be a projection)
>> depending on the system of course, but would be good to compare
>> with other TB-fitting codes which use such atomic-orbital basis
>> to represent the Hamiltonian.
> To do this, we normally choose trial functions that have the
> desired chemical symmetry, and then do zero iterations of the
> maxloc procedure.  That is, we use the WFs that are obtained
> just by projection on the trial functions.  We also include
> unoccupied bands if needed to "complete the shell" of WFs on
> each atom.  Because we skip the iterative localization, these
> may not be quite as localized as the MLWFs, but they may be
> good for your purposes.
> David
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