[DFTB-Plus-User] Spin-polarized cal. in DFTB+

[Benjamin Hourahine]

Hi,

It is also possible, as you have RelaxTotalSpin = Yes that the system has relaxed to a non-magnetic state. If you check the number of up and down electrons in detailed.out ("Nr. of electrons") this will show whether that happened.

If so, you might want to keep the total spin fixed until convergence and then either make separate calculations for different numbers of unpaired spins, or restart from your converged result and only then allow the spin polarisation to relax.

Regards,

Ben

Dr. B. Hourahine
Senior Lecturer and Director of Student Support
Department of Physics, SUPA
University of Strathclyde, John Anderson Building,
107 Rottenrow, Glasgow G4 0NG, UK.
+44 (0)1415483366, benjamin.hourahine at strath.ac.uk
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________________________________
From: DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of toufik essakhri <tousak at hotmail.fr>
Sent: 29 January 2025 09:02
To: User list for DFTB+ related questions <dftb-plus-user at mailman.zfn.uni-bremen.de>
Subject: Re: [DFTB-Plus-User] Spin-polarized cal. in DFTB+

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Hi Channyung,
Your system may converge to an antiferromagnetic alignment.
Please check detailed.out file to see whether it is AFM or NM.
Regards,
Toufik

________________________________
De : DFTB-Plus-User <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> de la part de Channyung Lee <fwangsubang at gmail.com>
Envoyé : mercredi 29 janvier 2025 02:28
À : dftb-plus-user at mailman.zfn.uni-bremen.de <dftb-plus-user at mailman.zfn.uni-bremen.de>
Objet : [DFTB-Plus-User] Spin-polarized cal. in DFTB+

Hi all,

I am currently performing DFTB+ calculations for oxides including Fe such as Fe₂O₃ using the following spin-polarized setup. However, I am encountering an issue where the Spin up and Spin down band structures appear identical, which suggests that spin polarization is not correctly applied. I would like to confirm whether my settings are correct or if any modifications are needed.

Below, I've attached an example input for Fe2O3. (Fe 4 O 6)

SpinPolarisation = Colinear { UnpairedElectrons = 20.0 RelaxTotalSpin = Yes InitialSpins = { AtomSpin = { Atoms = 1:4 SpinPerAtom = 5.0 } AtomSpin = { Atoms = 5:10 SpinPerAtom = 0.0 } } }

I would appreciate any guidance on how to resolve this issue. Should I modify the spin constants, Slater-Koster files, or initial spin configuration?

Best,

Channyung.
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