[QE-users] Anisotropic exchange calculation

[BARRETEAU Cyrille]

Dear Dorye

Could you be more explicit?
If you want to estimate J exchange parameters from energy differences of  collinear states (using a super cell and various UP and DN configurations) you do not need any non-collinear calculation.
I you want to use a non-collinear approach with small deviation from a given stable (or metastable state) I would suggest to use a penalization technique (atomic theta..) and map it onto an Heisenberg Hamiltonian by fitting an E(theta) for example.

Cyrille


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Cyrille Barreteau
CEA Saclay, IRAMIS, SPEC Bat. 771
91191 Gif sur Yvette Cedex, FRANCE
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+33 1 69 08 38 56 /+33  6 47 53 66 52  (mobile)
email:     cyrille.barreteau at cea.fr
Web:     http://iramis.cea.fr/Pisp/cyrille.barreteau/
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De : users [users-bounces at lists.quantum-espresso.org] de la part de Dorye Esteras Cordoba [dorye.esteras at uv.es]
Envoyé : lundi 16 novembre 2020 17:00
À : users at lists.quantum-espresso.org
Objet : [QE-users] Anisotropic exchange calculation

Dear community,

I am interested in calculating the CrBr3 J exchange parameters of an anisotropic Heisenberg Hamiltonian as it is shown in this paper:
https://doi.org/10.1039/C2DT31662E (Equations A16 and A17 on section D in the appendix)
 My idea would be to perform a collinear spin-polarized scf calculation (i.e. using scalar relativistic pseudopotentials), and then perform a non collinear nscf calculation for each of the spin configurations, following a similar procedure as in the MAE example https://gitlab.com/QEF/q-e/-/tree/f184591e9f34cfcc7767505a23977a92286e8ba6/PP/examples/ForceTheorem_example
Would this be reasonable or should I do a non collinear scf calculation for each scenario and extract Jxx,Jyy,Jzz from the total energies? Has someone experience with this kind of calculations?

Thank you in advance
Dorye L. Esteras
Predoctoral researcher
University of Valencia







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