[Wannier] Convergence problem of wannierisation

[nicolas poilvert]

Dear Reza,

For the first question, I don't know if you are talking about methodology or
technical details.
If it is about methodology, then I would say that the calculation of the
Quantum Conductance
can be done in 2 approches. The first one would be called "waveguide
approach" in which the
Bloch states are used to compute the "transmission function" of the system.
The second
approach is a "tight-binding approach" in which the Hamiltonian matrix in a
localized basis
is used to compute the same "transmission function". Both approaches are
actually mathematically
equivalent and so if you would use two different computer codes each
focusing on one of the
two above mentioned "approach" to compute the conductance, then the answer
should be the
same!

For the second question, I am a little unsure of what you are asking. If by
the K-mesh you mean
the uniform K-mesh used at the Non-Self-Consistent step before the
Wannierisation with Wannier90
then YES, this mesh in PWscf determines the quality of the computed MLWF. If
you are referring
to the Self-Consistent step, the mesh at this step can be whatever you want,
knowing that the
important thing to keep in mind is to obtain a well-converged ground state
charge density.

Cheers,

Nicolas

On Tue, Dec 1, 2009 at 1:53 PM, Reza Rasuli
<rezarasuli at physics.sharif.edu>wrote:

> Dear all
> Can one answer this please?
> 1- What errors would a Bloch orbital approach in a periodic cell give, for
> calculation of conductance, compared to the MLWF?
> 2- Does the K-mesh in PWSCF input depend on the MLWF basis? Is the
> convergence alluded to better, compared to a plane-wave basis?
> I will be grateful if you respond me.
> --
> Reza Rasuli
>
>
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>


-- 
POILVERT Nicolas
PhD candidate,
Dpt of Materials Science and Engineering
Massachusetts Institute of Technology
77, Massachusetts avenue
Cambridge, MA 02139
USA
work: (617) 452-4212
nicolas.poilvert at gmail.com
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