[Wien] Magnetocrystalline anisotropy

Tue Jan 16 18:02:23 CET 2018

Dear Peter and Laurence

Thank you for your replies. Using the following strategy it seems to 
work nicely (preliminary results):

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
x lapw2 -so -up  -c
x lapw2 -so -dn  -c

In other words, we do not put -orb in lapwso. It seems that this option 
was leading to problems depending on the magnetic system.

Best Regards
Xavier

Le 16/01/2018 à 17:57, William Lafargue-dit-Hauret a écrit :
>
> Dear Profs. Blaha and Marks,
>
> Thank you for your advices. I have a question regarding your comment 
> on the EECE case.
>
> The resulting effective potential of LDA+U and EECE corrections is 
> decomposed in vorb files, but I don't understand why the spin-coupling 
> file case.vorbud shouldn't appear in the second case.
>
> I have a second question regarding the reading of these orbital 
> potential files. We noticed the orb program read only the real part, 
> neglecting the imaginary one (Prof. Marks already noticed it in the 
> source code). Due to our energy scale which is tiny, could we expect 
> an impact of such approximation ? Considering your last comments, it 
> seems not due to the execution of the orb program only in lapw1 and 
> not during the perturbative procedure.
>
> Thank you by advance.
>
> All the best,
>
> William Lafargue-dit-Hauret
>
>
> Le 16/01/2018 à 17:05, Xavier Rocquefelte a écrit :
>> 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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>>>>>>
>>>>>
>>>>
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>
> -- 
> William LAFARGUE-DIT-HAURET
> PhD Student
> --------------------------------------------------
> Institut des Sciences Chimiques de Rennes UMR 6226
> Equipe Chimie Théorique Inorganique
> Université de Rennes 1 - Campus de Beaulieu
> 35042 Rennes, France
> Building 10B, Desk 211
> Phone: +33 (0)2.23.23.57.91
> Email:william.lafargue-dit-hauret at univ-rennes1.fr
>
>
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