[QE-users] Magnetic anisotropy energy in QE 6.3

Thu Jul 12 14:04:42 CEST 2018

Oh, that's great! Since I am using a supercell which is a 2x2 repetition of
the unit cell for Cu2N (which is, itself, built upon a 2x2 repetition of
the Cu(100) slab without N atoms), I suppose I won't have to go much
further than the k-point sampling I am currently using for the
non-spin-polarized relaxation of the supercell. I will, however, perform
convergence tests.

Merci beaucoup for the comments!

Best,

Marcos

On Thu, Jul 12, 2018 at 1:57 PM, BARRETEAU Cyrille <cyrille.barreteau at cea.fr
> wrote:

> For the Co slab of the example I would suggest 20x20x1 kpoints for scf (no
> SOC) calculation and 40x40x1 kpoints for the nscf (with SOC) calculations.
> But you should check convergence.
>
> For bulk calculations MAE is extremely complicated to extract since in
> cubic systems the MAE is of the order of 10^(-5)eV!!! Almost impossible to
> achieve a converged result!
>
> Cyrille
>
>
> ========================
> *Cyrille Barreteau*
> CEA Saclay, IRAMIS, SPEC Bat. 771
> 91191 Gif sur Yvette Cedex, FRANCE
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +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/
> ========================
> ------------------------------
> *De :* users [users-bounces at lists.quantum-espresso.org] de la part de
> Marcos Veríssimo Alves [marcos.verissimo.alves at gmail.com]
> *Envoyé :* jeudi 12 juillet 2018 13:32
>
> *À :* Quantum Espresso users Forum
> *Objet :* Re: [QE-users] Magnetic anisotropy energy in QE 6.3
>
> Thanks for the tip, Cyrille. Should it be increased in the SCF calculation
> or in the NSCF one? I would suppose the latter, but of course it's good to
> hear the opinion of an expert before wasting human and computer time.
>
> Indeed, there's this paper by Daalderop et al. for bulk Fe, Ni and Co (if
> I'm not mistaken) where they highlight this - 100^3 k-points! I suppose
> that this would be equivalent to having a 100 x 100 x 100 Monkhorst-Pack
> grid?
>
> From your experience, maybe you could comment on the number of k-points
> needed for my particular calculations. The system am working on is a Fe
> adatom on a Cu2N surface over Cu(100). I am using a quite large vacuum
> layer, of about 18 Ang, along the z direction of a tetragonal cell - would
> a dense mesh of k-points then need to be considered only for the kx and ky
> directions of the BZ?
>
> Best,
>
> Marcos
>
>
>
> On Thu, Jul 12, 2018 at 12:22 PM, BARRETEAU Cyrille <
> cyrille.barreteau at cea.fr> wrote:
>
>> Of course to get reliable magnetic anisotropy you should drastically
>> increase the number of Kpoints with respect to the example..
>>
>> Cyrille
>>
>> ========================
>> *Cyrille Barreteau*
>> CEA Saclay, IRAMIS, SPEC Bat. 771
>> 91191 Gif sur Yvette Cedex, FRANCE
>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> +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/
>> ========================
>> ------------------------------
>> *De :* users [users-bounces at lists.quantum-espresso.org] de la part de
>> Marcos Veríssimo Alves [marcos.verissimo.alves at gmail.com]
>> *Envoyé :* jeudi 12 juillet 2018 12:10
>>
>> *À :* Quantum Espresso users Forum
>> *Objet :* Re: [QE-users] Magnetic anisotropy energy in QE 6.3
>>
>> Hello Cyrille and Paolo,
>>
>> Thanks for the quick response. I was interested really about the inner
>> workings, which should be described in the paper that Cyrille mentioned. I
>> will take a look at it. The actual execution of the calculation should be
>> quite straightforward, from what I saw yesterday in the examples folder.
>>
>> Once again, thanks to both of you for the response. If I run into any
>> problems I'll ask, but hopefully all will be fine.
>>
>> Best,
>>
>> Marcos
>>
>> Em qui, 12 de jul de 2018 10:37, BARRETEAU Cyrille <
>> cyrille.barreteau at cea.fr> escreveu:
>>
>>> Hi Marcos
>>>
>>> The implementation of the Force Theorem has been described in the
>>> following paper:
>>> https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.205409
>>>
>>> The procedure is the following:
>>> first perform a scf calculation with scalar relativistic pseudo
>>> then perform  nscf calculation with fully relativistic pseudo (option
>>> lforcet=.true., nosym=.true') starting from previous scf charge
>>> (startingpot='file') with various spin orientations (theta=0,90 for example)
>>> Finally perform a projwfc calculation with  lforcet=.true. and the value
>>> of the Fermi level from the nscf calculation (same ef_0 for all
>>> calculations).
>>>
>>> Then you get a file with the energy decomposed over the various atoms
>>> and orbitals of the system..
>>> The anisotropy is obtained by difference between the different spin
>>> orientations.
>>>
>>> hope it helps..
>>>
>>> Cyrille
>>>
>>>
>>> ========================
>>> *Cyrille Barreteau*
>>> CEA Saclay, IRAMIS, SPEC Bat. 771
>>> 91191 Gif sur Yvette Cedex, FRANCE
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> +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/
>>> ========================
>>> ------------------------------
>>> *De :* users [users-bounces at lists.quantum-espresso.org] de la part de
>>> Paolo Giannozzi [p.giannozzi at gmail.com]
>>> *Envoyé :* jeudi 12 juillet 2018 10:04
>>> *À :* Quantum Espresso users Forum
>>> *Objet :* Re: [QE-users] Magnetic anisotropy energy in QE 6.3
>>>
>>> here? PP/examples/ForceTheorem_example/
>>>
>>> P.
>>>
>>> On Thu, Jul 12, 2018 at 10:01 AM, Marcos Veríssimo Alves <
>>> marcos.verissimo.alves at gmail.com> wrote:
>>>
>>>> Hi all,
>>>>
>>>> Browsing QE 6.3's documentation, I saw that MAE can be calculated as a
>>>> post-processing step to a pw.x scf calculation. What is the exact procedure
>>>> followed? I.e., in the post-processing calculation is the spin density
>>>> rotated, and then SOC is included? Is there any reference that details the
>>>> procedure used when the MFT is applied in Espresso?
>>>>
>>>> Best regards,
>>>>
>>>> Marcos
>>>>
>>>> _______________________________________________
>>>> users mailing list
>>>> users at lists.quantum-espresso.org
>>>> https://lists.quantum-espresso.org/mailman/listinfo/users
>>>>
>>>
>>>
>>>
>>> --
>>> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
>>> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
>>> Phone +39-0432-558216, fax +39-0432-558222
>>>
>>> _______________________________________________
>>> users mailing list
>>> users at lists.quantum-espresso.org
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>>
>>
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