[Wien] Magnetocrystalline anisotropy

Tue Jan 16 17:05:43 CET 2018

I was not clear Peter. I clarify the way we proceed.

We do runsp_lapw -eece -p -ec 0.00001 -NI

Then for larger EMAX and kmesh without SO we do :

x lapw1 -up -c -orb
x lapw1 -dn -c -orb

And for the different magnetization directions we do:

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

Le 16/01/2018 à 16:58, Peter Blaha a écrit :
> Hups: If this is true, you are counting the orbital potential twice !
>
> -orb should only be present in the lapwso step.
> (And in fact, the lapw1 steps need to be done just once for the 
> increased k-mesh; but not when changing the M-direction in case.inso)
>
> Please check the presence of case.vorbud. It must not be there for EECE.
>
> You could also test Laurence suggestion, running:
>
> x lapw1 -up/dn -orb
> x lapwso -up      (no -orb !!!)
>
> and see of it makes a difference.
>
> On 01/16/2018 04:52 PM, Xavier Rocquefelte wrote:
>> 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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>>>>
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