[Wannier] Fwd: Extracting tight binding Parameters
Jesse Vaitkus
jesse.vaitkus at rmit.edu.au
Tue Jun 28 09:15:38 CEST 2016
Hello Christopher,
a few things. Firstly, did you check that before truncating your
interactions whether the band structure was reconstructed? This is a very
important first step, if these are not recreated then you have bigger
problems. Secondly, you have not reported the average spread of the WFs
which is the metric used to work out how localised they are, if it exceeds
the nearest neighbour distance then you likely need next nearest neighbour.
Thirdly, you have not shown us which bands you wish to disentangle, if
they're entangled you might need to finesse your frozen window. Fourthly,
2,8 and 3,8 don't necessarily need to be the same; 2,8 and 8,2 and 3,8 and
8,3 need to be hermitian conjugates of each other and no, w90 does not
impose symmetry, something that I would so absolutely love. Lastly,
unfortunately the way in which w90 orders your wannier functions need not
be how you want them ordered so what you call anion and cation might not be
so (just check their output positions and then you'll know, assuming that
you haven't already done this and I'm out of line). An 'easy way' to
enforce your own personal ordering is to start a new run using the
positions of the converged WFs you should be able to tell which atoms these
correspond to and then use a strong guiding centre constraint.
I hope my list has helped you. Best of luck.
Cheers,
Jesse Vaitkus
On 28 June 2016 at 03:13, Christopher Pashartis <cpashartis at gmail.com>
wrote:
> Hello,
>
> I'm new to using wannier90 and I am trying to extract tight binding
> parameters for use in my code. Unfortunately, I cannot seem to reproduce
> the correct tight binding result that I get from my DFT code (not QE). If
> someone can verify, point me to a proper example, or correct me it would be
> greatly appreciated.
>
> I've reduced my Hamiltonian to nearest neighbour interactions only,
> therefore, since I am using a zinc blende structure these are the
> corresponding matrix elements I am interested in:
>
> 0 0 0 1 1 -4.324417 -0.000000
> 0 0 0 2 1 0.000002 -0.000000
> 0 0 0 3 1 -0.000000 0.000000
> 0 0 0 4 1 -0.000001 0.000000
> 0 0 0 5 1 -1.472555 0.000000
> 0 0 0 6 1 -1.157538 0.000000
> 0 0 0 7 1 1.157536 -0.000000
> 0 0 0 8 1 1.157537 -0.000000
> 0 0 0 1 2 0.000002 0.000000
> 0 0 0 2 2 2.843276 -0.000000
> 0 0 0 3 2 0.000000 -0.000000
> 0 0 0 4 2 0.000000 0.000000
> 0 0 0 5 2 1.067338 0.000000
> 0 0 0 6 2 0.180666 0.000000
> 0 0 0 7 2 -1.181808 -0.000000
> 0 0 0 8 2 -1.181808 -0.000000
> 0 0 0 1 3 -0.000000 -0.000000
> 0 0 0 2 3 0.000000 0.000000
> 0 0 0 3 3 2.843276 -0.000000
> 0 0 0 4 3 0.000000 -0.000000
> 0 0 0 5 3 -1.067337 -0.000000
> 0 0 0 6 3 -1.181809 -0.000000
> 0 0 0 7 3 0.180665 0.000000
> 0 0 0 8 3 1.181808 0.000000
> 0 0 0 1 4 -0.000001 -0.000000
> 0 0 0 2 4 0.000000 -0.000000
> 0 0 0 3 4 0.000000 0.000000
> 0 0 0 4 4 2.843276 -0.000000
> 0 0 0 5 4 -1.067337 -0.000000
> 0 0 0 6 4 -1.181809 -0.000000
> 0 0 0 7 4 1.181808 0.000000
> 0 0 0 8 4 0.180665 0.000000
> 0 0 0 1 5 -1.472555 -0.000000
> 0 0 0 2 5 1.067338 -0.000000
> 0 0 0 3 5 -1.067337 0.000000
> 0 0 0 4 5 -1.067337 0.000000
> 0 0 0 5 5 -8.772213 0.000000
> 0 0 0 6 5 -0.000003 0.000000
> 0 0 0 7 5 -0.000003 -0.000000
> 0 0 0 8 5 -0.000003 -0.000000
> 0 0 0 1 6 -1.157538 -0.000000
> 0 0 0 2 6 0.180666 -0.000000
> 0 0 0 3 6 -1.181809 0.000000
> 0 0 0 4 6 -1.181809 0.000000
> 0 0 0 5 6 -0.000003 -0.000000
> 0 0 0 6 6 0.872588 0.000000
> 0 0 0 7 6 0.000000 0.000000
> 0 0 0 8 6 0.000000 -0.000000
> 0 0 0 1 7 1.157536 0.000000
> 0 0 0 2 7 -1.181808 0.000000
> 0 0 0 3 7 0.180665 -0.000000
> 0 0 0 4 7 1.181808 -0.000000
> 0 0 0 5 7 -0.000003 0.000000
> 0 0 0 6 7 0.000000 -0.000000
> 0 0 0 7 7 0.872588 0.000000
> 0 0 0 8 7 -0.000000 0.000000
> 0 0 0 1 8 1.157537 0.000000
> 0 0 0 2 8 -1.181808 0.000000
> 0 0 0 3 8 1.181808 -0.000000
> 0 0 0 4 8 0.180665 -0.000000
> 0 0 0 5 8 -0.000003 0.000000
> 0 0 0 6 8 0.000000 0.000000
> 0 0 0 7 8 -0.000000 -0.000000
> 0 0 0 8 8 0.872588 0.000000
>
> From my interpretation, the corresponding LCAO parameters would be:
> E_sa E_sc E_pa E_pc ssSigma sapcSigma scpaSigma ppSigma ppPi
> -8.77210 -4.32453 0.87263 2.84323 -1.47257 1.06736 1.15752 0.18067 1.1818
>
> Where c corresponds to the cation (in this case it should be the 1-4
> functions) and a is the anion (5-8 functions).
>
> With regards to my parameters above, does Wannier90 already build in
> symmetry operations? For example at (2,8) vs (3,8) these should be the same
> value (+ or - not both) unless I'm misinterpreting what this file truly
> presents, so which should it be?
>
> Any help would be greatly appreciated!
>
> Christopher Pashartis
> Masters Candidate
> McMaster University
>
>
>
>
>
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>
>
--
————————————————————————————————
Mr. Jesse Vaitkus MAIP
BAppSc(Phys) Hons, BAppSc(Nano)
PhD candidate
Room 14.6.02
Chemical and Quantum Physics
School of Applied Sciences
RMIT University
Victoria 3001
Australia
jesse.vaitkus at rmit.edu.au
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