[Wien] Magnetocrystalline anisotropy

[Xavier Rocquefelte]

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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