[Wannier] Hamiltonian in MLWF basis

[Nicola Marzari]

Dear Jian Xin,

have a look at this

http://www.chrismarianetti.org/static/publications/prb_90_165125_2014_wang.pdf


nicola


On 02/12/2014 06:11, Zhu, Jianxin wrote:
> Dear Jonathan and Respectful Wannier Users,
>
>
> I have recently been using wien2wannier (thanks to Jan Kunes, Philipp
> Wissgott, and Elias Assmann) together with wannier90 for several physical
> systems.
>
> Noticeably, for some systems (e.g., tetragonal LaOFeAs etc.), the
> Hamiltonian matrix elements in the MLWF basis are diagonal in the WF
> orbitals on the same atomic site.
> However, for some other systems (e.g., hexagonal YCo5 etc.), the
> Hamiltonian matrix elements in the MLWF basis are not diagonal in the WF
> orbitals on the same atomic site.
> The latter case is surprising to me because the conventional tight-binding
> approximated Hamiltonian (based on a local atomic orbitals) are always
> diagonal on the same atomic site.
>
> I check back to the paper by Mostofi et al., Computer Physics
> Communications 178. 685 (2008), and see the Hamiltonian is derived from
> rotated Bloch states through U^k and U^dis(k) (cf. Eqs. (19-20) in the
> above mentioned paper).
> Due to these U^k and U^dis(k), it seems to me that there is no guarantee
> that the Hamiltonian matrix elements must be diagonal in the basis of MLWF
> on the same site.
> Do I understand correctly?
>
> Have you encountered this kind of situations in applying MLWF to practical
> systems?
>
> Your suggestions/thoughts are appreciated.
>
> Best,
>
> Jianxin
>
> P.S.: Elias, I cc this message to you in case you also have suggestions.
>
>
>
> #################################
> Jian-Xin Zhu, Ph.D
> Theoretical Division, MS B262
> Los Alamos National Laboratory
> Los Alamos, New Mexico 87545
> Phone: (505) 667 2363 (T-4);
> (505) 667 6602 (CINT)
> Fax: (505) 665 4063
> Email (main): jxzhu at lanl.gov
> Email (backup): physjxzhu at gmail.com
> URL: http://theory.lanl.gov
> #################################
>
>
>
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-- 

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Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL