[Wien] Magnetocrystalline anisotropy

[Peter Blaha]

Hallo Xavier,

Looks rather strange.

Eventually I would have expected problems both, in 16.1 and 17.1 (but 
not 14.2) due to the off-diagonal density matrices. But this should 
concern ONLY LDA+U, not -eece.

Just to be sure:

I expect you do SO non-selfconsistent, so vorbup/dn(du) files are always 
the same ??  (just running lapwso and lapw2 -so)

Did you make sure that for -eece -so, case.vorbud is NOT present (from 
previous LDA+U).

Peter


On 01/16/2018 02:50 PM, Xavier Rocquefelte 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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>>>
>>>
>>>
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>>
>>
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> 
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                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-165300             FAX: +43-1-58801-165982
Email: blaha at theochem.tuwien.ac.at    WIEN2k: http://www.wien2k.at
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