[Wien] Energy convergence with spin-orbit

[Laurence Marks]

The energy is not always a good measure. Do, for instance if the impurity
is atom 1,
 grep :POM001DN *scf

Is this oscillating or slowly changing? Check the other terms I suggested.

N.B., remember that you have periodic continuation in the surface plane, so
unless you have a large supercell you are imposing FM ordering.

On Fri, Feb 12, 2016 at 9:03 AM, Islam, Md F <islamm at uta.edu> wrote:

> 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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-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu
Corrosion in 4D: 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
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