[Wien] Magnetocrystalline anisotropy

[Laurence Marks]

I may annoy Peter with the comment below, so it goes....

Personally I have some reservations about the consistency between the
orbital potential and time-reversal operations in -so. Three possible
tests:

a) Reduce the symmetry to P1 and run. While this is slower, I believe
your test case is small so this should not matter.
b) Hack the runsp_lapw script so that -orb is applied to lapw1, not in lapwso
c) Run without the up/dn component (-noorbud)

On Tue, Jan 16, 2018 at 7:50 AM, Xavier Rocquefelte
<xavier.rocquefelte at univ-rennes1.fr> wrote:
> Here is a document showing the results graphically.
>
> https://filesender.renater.fr/?s=download&token=8ac3a214-edfa-4894-fa1f-27aba5a5522f
>
> It really looks like the problem we had before (using bad kmesh).
>
> We test it on two different compounds and in both cases WIEN2k_16 gives a
> correct picture and not WIEN2k_17.
>
> We are now comparing the two versions of the code.
>
> Regards
>
> Xavier
>
>
> Le 16/01/2018 à 12:10, Xavier Rocquefelte a écrit :
>
> Dear All
>
> Finally the problem is not completely solved.
>
> More precisely, when we are doing GGA+SO calculations and using a correct
> kmesh (no temporal symmetry), we obtain a symmetric magnetocrystalline
> anisotropy, namely same MAE along [0 1 0] and [0 -1 0].
>
> In contrast, when we are doing GGA+U+SO or EECE+SO with a correct kmesh we
> still obtain non-symmetric MAE, namely MAE along [0 1 0] and [0 -1 0] are
> different.
>
> In addition, the so obtained MAE looks similar to the ones obtained in
> GGA+SO with a bad kmesh (including temporal symmetry).
>
> At this moment, we are checking all the recent modifications in SRC_ORB and
> SRC_LAPW2 related to the manipulation of case.vorbup, case.vorbdn and
> case.vorbud files.
>
> Surprisingly, the EECE+SO calculations in WIEN2k_16 are symmetric, while not
> in WIEN2k_17.
>
> Next soon ... I hope.
>
> Xavier
>
>
> Le 10/01/2018 à 15:10, Xavier Rocquefelte a écrit :
>
> Dear All
>
> The problem is solved and was related to one stupid human mistake.
>
> It was necessary to generate a kmesh without adding inversion
> (time-inversion symmetry).
> Indeed, as mentionned in the userguide when using kgen program:
>
> "add inversion" ? This is asked only when inversion is NOT present.
>
> Say "YES" in all cases except when you do spin-polarized (magnetic)
> calculations WITH spin-orbit coupling (this breaks time-inversion symmetry
> and thus one MUST NOT add inversion symmetry (eigenvalues at +k and -k may
> be different).
>
> If you properly generate the kmesh for the spin-orbit calculations by doing
> : x kgen -fbz, then you obtain a symmetric magnetic anisotrop. In conclusion
> the asymmetry I obtained was due to an improper definition of the kmesh
> (adding artificially time-inversion).
>
> I want to thank all the participants who answered to my question. It was
> essential to identify such a mistake which has a huge impact on the results.
>
> Best wishes
>
> Xavier
>
>
>
> Le 10/01/2018 à 10:47, Xavier Rocquefelte a écrit :
>
> Dear Lyudmila
>
> The fact we have a small angle with axes is expected (also observed
> experimentally). It is related to the monoclinic symmetry of the system
> which permits it. However, you gave me an idea that I will test now and
> comment soon ;)
>
> Cheers
>
> Xavier
>
> Le 10/01/2018 à 10:40, Lyudmila a écrit :
>
> 10.01.2018 13:36, Lyudmila wrote:
>
> I see in the FM calculation also a slightly non-symmetric curve, isn't it?
>
>
> I meant the small angle with axes.
>
> Best wishes
> Lyudmila Dobysheva
>
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-- 
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what
nobody else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A