[Wien] Magnetocrystalline anisotropy
Peter Blaha
pblaha at theochem.tuwien.ac.at
Tue Jan 16 16:58:30 CET 2018
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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--
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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