Hi Cyrille,
Since magnetic anisotropy energy is very small (~0.01 meV per atom in my
system), do I need to use higher cutoff energies to account for such
small energy scale?
best,
Yun-Peng
On 09/12/2015 03:30 PM, BARRETEAU Cyrille wrote:
Dear Yun-Peng,
>From experience I can just say that calculation using
fully-relativistic PP can be really difficult to converge and
sometimes almost impossible to achieve the desired accuracy
(especially since magneto-crystalline anisotropy requires very strict
convergence thresholds). You can play with broadening and k points
sampling.
Cyrille
========================
*Cyrille Barreteau*
CEA Saclay, IRAMIS, SPECBat. 771
91191 Gif sur Yvette Cedex, FRANCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
DTU Nanotech
Ørsteds Plads, building 345E
DK-2800 Kgs. Lyngby, DENMARK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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email: [email protected] /[email protected]
Web: http://iramis.cea.fr/Pisp/cyrille.barreteau/
========================
------------------------------------------------------------------------
*De :* [email protected] [[email protected]] de la
part de yuewen.fang [[email protected]]
*Envoyé :* samedi 12 septembre 2015 20:42
*À :* pw_forum
*Objet :* Re: [Pw_forum] magnetic anisotropy calculation using
fully-relativistic PPs
Hi, Yun-Peng,
Thanks for your feedback. It depends on the matter which you are
interested in. I think this paper (Phys. Rev. B 86, 085135 (2012))
can help you.
Bests
Fang
------------------------------------------------------------------------
Yue-Wen FANG, PhD candidate
East China Normal University <http://english.ecnu.edu.cn/>
< peter <mailto:[email protected]>> 2015-09-13 02:16:28 wrote:
Thank you for your suggestions!
I tried using a small mixing beta (0.1~0.2), and tried using
reasonable cutoff energies (ecutwfc=50, ecutrho=500), now the
convergence is much better than before (converged down to 10^-6 Ry).
Another question is, I can find ultra-soft and PAW
pseudopotentials, which one is better for spin-orbit calculations?
I am using PBE XC functional.
best,
Yun-Peng
On 09/11/2015 08:08 PM, yuewen.fang wrote:
Dear Yun-Peng,
Plz try to decrease mixing and perform some convergence tests for
your cutoff energy to remove the oscillation of the energy! In
addition, this oscillation could also be caused by the
unreasonable smearing methods for metals.
Bests
Fang
------------------------------------------------------------------------
Sent from YoMail <http://www.yomail.com/?utm_source=signature>
< Peter Cybertron <mailto:[email protected]>> 2015-09-12
03:10:31 wrote:
Hi,
I am working in University of Florida as a postdoc.
I am exploring the spin-orbital calculations using pwscf, and I
encounter a very slow convergence like this:
> grep estimated scf.out
estimated scf accuracy < 0.00000004 Ry
... (100 similar lines)
estimated scf accuracy < 0.00000003 Ry
> grep "total energy" scf.out
...
total energy = -3667.91077719 Ry
total energy = -3667.91078176 Ry
total energy = -3667.91077642 Ry
total energy = -3667.91078300 Ry
Although the convergence of total energy seems OK (down to
0.00001 Ry ~
0.0001 eV = 0.1 meV), I still feel uncomfortable since I
never encounter
such a problem without spin-orbit interactions.
I downloaded the ultrasoft and PAW pseudopotentials from
PSLib and I am
using the PBE flavor of XC functional. The system I am
studying is a two
dimensional magnetic insulator.
The parameters I am using are:
constrained_magnetization = 'total direction'
fixed_magnetization(3) = 0.0
lambda = 0.2
ecutwfc = 30.0 ,
ecutrho = 300.0 ,
occupations = 'smearing' ,
degauss = 0.005,
smearing = 'mv' ,
nosym=.true.
mixing_mode = 'local-TF' ,
mixing_beta = 0.9 ,
diagonalization = 'david' ,
Which parameter on earth keep my calculations non-converged?
Best,
Yun-Peng
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