[Wien] Magnetocrystalline anisotropy

[Xavier Rocquefelte]

Dear Peter

You are totally correct. We are doing SO non-selfconsistent by using a 
standard procedure for EECE calculations:

runsp_lapw -eece -p -ec 0.00001 -NI

and then we estimate the MAE using this non-SCF procedure :

Increase EMAX in case.in1c - increase kmesh if needed ....

x lapw1 -up -c -orb
x lapw1 -dn -c -orb
x lapwso -c -up  -orb
x lapw2 -so -up  -c
x lapw2 -so -dn  -c

Such a procedure was working nicely in previous WIEN2k versions.
Best Regards
Xavier



Le 16/01/2018 à 16:34, Peter Blaha a écrit :
> 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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