Extending TB2J to LCAO-GTO

[genijalac11]

Dear Xu He,
I hope that you are doing well!
I was wondering if there is already some development on extending TB2J to a LCAO-GTO basis set? I am thinking in particular about the CRYSTAL code.
If not already in consideration, would a wannierization step would be necessary or are the Gaussian type functions (orbitals) already local enough for the formalism to work comparatively with the NAOs?
Cheers,
Aleks

[mjv500]

Hello, Tb2j already has several interfaces to lcao basis sets with siesta open mx and abacus. It should be fairly easy to extend it to Crystal and GTOs, indeed. I would even recommend not going through the wannier functions. They are nice, complete in their occupied Hilbert space, but have limitations and can be hard to converge properly, centered on the atoms etc. These are automatic for LCAO. Have a look at the siesta interface and send us your proposition or a MR for crystal. Best Matthieu ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Professor Matthieu J Verstraete Fellow, American Physical Society <https://www.aps.org> Chair, Steering Committee, European Theoretical Spectroscopy Facility <https://www.etsf.eu> Alumnus Fellow, Young Academy of Europe <https://www.yacadeuro.org> <http://yacadeuro.org/> Institute for Theoretical Physics (ITP) Department of Physics Buys Ballot Gebouw/Building, Princetonplein 5, office University of Utrecht, 3584 CC Utrecht Phone: +31 30 253 5926 Secretariat: +31 30 253 5929 and ***@***.*** Group web page (Liège): http://www.nanomat.ulg.ac.be/ Nanomat lab, Q-Mat center, Université de Liège Département de Physique, Bat. B5a, 4/50 Allée du 6 août, 19 B-4000 Sart Tilman, Liège Belgium Phone : +32 4 366 90 17 European Theoretical Spectroscopy Facility <https://www.etsf.eu> (ETSF) Mail : ***@***.*** ***@***.*** ***@***.***

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On Sat, Jul 19, 2025, 13:43 genijalac11 ***@***.***> wrote: Dear Xu He, I hope that you are doing well! I was wondering if there is already some development on extending TB2J to a LCAO-GTO basis set? I am thinking in particular about the CRYSTAL code. If not already in consideration, would a wannierization step would be necessary or are the Gaussian type functions (orbitals) already local enough for the formalism to work comparatively with the NAOs? Cheers, Aleks — Reply to this email directly, view it on GitHub <#71>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABWOT34OACMIHWB2NOVLULT3JIVPBAVCNFSM6AAAAACB4Q2SYCVHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZYGYYDEOBSGI> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[genijalac11]

Hi Matthieu,
Thanks for the reply even on a Saturday :D
I'll have a look and hopefully be back with something useful!
Cheers,
Aleks

[mailhexu]

Hello,
What TB2J requires from the DFT code is the Khon-Sham Hamiltonian and the overlap matrices (if the basis are non-orthogonal), and some basic information about the basis set ( the atom each basis function belongs to). If you know how to do that the implementation can be easy. But I did not find these in the ouput from the CRYSTAL documentation.
Another option is to use the wavefunctions and the eigenvalues in the full BZ, which can be generated.
Best,
HeXu