[Wien] Energy convergence with spin-orbit

[Islam, Md F]

Hi Prof. Marks,

    Thanks for your comments. The calculation is with single impurity, so there is no issue with FM or AFM alignment.    
I also chose the magnetization such that symmetry is not broken for in-plane or out-of-plane orientation. This particular
calculation is done with Fe impurity but I have done the same set of calculations with Mn impurity on the same surface
(Bi2Se3) without any problem. I agree that it doesn't guarantee a solution for all calculations but I just wanted to make
sure I have explored all possibilities before give up on it. Here are some energies around which SCF is oscillating.


:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79554107
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79537485
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79534902

:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79494494
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79504374
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79510509

:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79523383
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79548735
:ENE  : ********** TOTAL ENERGY IN Ry =     -2381169.79554582

This is going on for several weeks, so it doesn't look like converging slowly.

Thanks,
Fhokrul


________________________________________
From: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at] On Behalf Of Laurence Marks [laurence.marks at gmail.com]
Sent: Friday, February 12, 2016 7:49 AM
To: A Mailing list for WIEN2k users
Subject: Re: [Wien] Energy convergence with spin-orbit

I have only done a few -so calculations, but from the list they seem to lead to problems. A few suggestions:

a) Check for user error when you setup the in plane calculation. Have you used the right symmetry reduction? This seems to be the most common issue.

b) Check that you are using the patches for issues in initso that have been posted.

c) Look if your calculation is oscillating or just veeeeeery slowly converging. You can do a grep on some of the moments such as :ORB, :POM, :SPI in case.scf. I have seen these only slowly converge as the occupied states change.

d) Think carefully about the physics of your problem. Some time ago I did a test LDA+U calculation for a Ni (metal) surface. It did not converge, which was OK. In Wien2k you are solving a fixed-point problem, and always assuming that such a solution exists. I do not believe that anything  guaruntees that a solution exists in all cases. ( This is different from doing a variational calculation.) Maybe with your distances your impurities want to have an AFM ordering in-plane, but you are preventing this.

These are just guesses, without more information it is hard to know.

---
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
http://www.numis.northwestern.edu
Corrosion in 4D http://MURI4D.numis.northwestern.edu
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody else has thought"
Albert Szent-Gyorgi

On Feb 12, 2016 06:19, "Islam, Md F" <islamm at uta.edu<mailto:islamm at uta.edu>> wrote:
Dear Wien2k users,

    I am trying to do a magnetic impurity calculation on a surface including spin-orbit coupling.
I set the energy and charge convergence to 0.00001 and 0.001, respectively. The calculation is
well converged if magnetization is in-plane but for out of plane magnetization it is not converging.
While charge satisfies convergence criterion very well, the energy keeps oscillating near the 3rd/4th
decimal places.. I tried with different mixing (MSR1: 0.05 to 0.01) but nothing seems to be working
for about 2 months. For larger mixing, job crashes with QTL-B error. I would appreciate if you can
give me some suggestion to resolve the problem.

   I am also wondering if anyone has done any anisotropy calculation with both self-consistent and
non self-consistent methods and whether they give the same anisotropy energy.


Thanks,
Fhokrul

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