[Wien] Query about SOC in WIEN2k
Rajiv Chouhan
chouhanrajiv14 at gmail.com
Mon Nov 7 04:04:21 CET 2016
Dear Peter and Xavier,
Thank you for the reply and detail suggestion for spin orbit coupling
method for two different methodology (Energy and force).
Can you please clarify my doubt in following points:
>>Increase the k-mesh (for the final low-symmetry struct file) to a very
good one AND TEST the convergence. of your results.
I can generate the P1 structure for the system, but how to get the
low-symmetry structure which is valid for all direction (001, 100, 010,
etc).
Is there any specific way of doing?
>> Since the E differences are very small, set the DEs in case.in1 to a
smaller value like:
0 -4.09 .0001 STOP 1
^^^^^^^ DE
Here do I need to set small increment for all the atomic orbitals which has
DE .ne. 0, or for only the specific orbitals which has STOP conditions?
>> During the process of initso_lapw
Here I have confusion in generating the case.inso file. I need more
clarification whether I should copy from SRC_templetes and modify
accordingly or we should generate case.inso with
interactive command initso_lapw? Can you explain case.inso file generation,
Like: when to select RLO for atoms? Do I need to keep kpoints same for all
directions (001, 010 etc)? Should
I generate case.inso file same way for the "force method" also, because as
far as I understood the force theorem is base on non-scf calculation, so
when we choose the new symmetry the
Eigenvalues for different directions changes a lot resulting bad
anisotropy.
P.S: Xavier I am trying to reproduce the result of the mentioned paper.
Thank you,
R. Chouhan
On Sat, Nov 5, 2016 at 4:13 PM, Xavier Rocquefelte <xavier.rocquefelte at univ-
rennes1.fr> wrote:
> Dear R. Chouhan
>
> Just to complete the very nice answer of Peter. I have used the force
> theorem as explained by Peter using GGA+U to estimate MCA and in the cases
> I have considered it works amazingly nicely.
>
> As Peter said, I was using P1 symmetry and checking carefully the
> convergency before including the spin-orbit effect along specific
> directions.
>
> Here is an example of what we obtained for CuO (Fig. 3). Similar results
> are obtained using on-site hybrid of GGA+U.
>
> http://www.nature.com/articles/ncomms3511
>
> Best Regards
>
> Xavier
>
>
>
> Le 05/11/2016 à 17:43, Peter Blaha a écrit :
>
>> There are a lot of problems in your calculations:
>>
>> Usually the energy difference between 2 such calculations is extremely
>> small and one must be very careful to get meaningful numbers.
>>
>> When you do initso for a spinpolarized system, the symmetry can be
>> reduced. In such cases you MUST take the newly generated struct file.
>>
>> > Do you want to use the new structure for SO calculations ? (y/N) N
>>
>> This is the wrong answer !
>>
>> In fact, one should even do the calculations for the different
>> magnetization directions with the same symmetry (eventually in P1). Thus
>> checkout what symmetries you get for the different directions and choose
>> the one which is compatible with all cases.
>> Check your case.inorb/dmc files in case that the number of atoms has been
>> changed.
>>
>> Important:
>> Increase Emax in case.in1 to a VERY large number (10 Ry), and test your
>> results with respect to this EMAX.
>> Increase the k-mesh (for the final low-symmetry struct file) to a very
>> good one AND TEST the convergence. of your results.
>>
>> With such a struct file you run again (in the same directory) the non-so
>> calculation to selfconsistency with a good k-mesh and good convergence:
>> runsp -orb -ec 0.000001 -cc 0.000001
>>
>> Since the E differences are very small, set the DEs in case.in1 to a
>> smaller value like:
>> 0 -4.09 .0001 STOP 1
>> ^^^^^^^ DE
>>
>> Once the non-so calculation is converged:
>>
>> save_lapw non_so
>>
>> Now the force theorem:
>> select 001 direction in case.inso
>> x lapw1 -up/dn
>> x lapwso -up -orb
>> x lapw2 -so -up/dn
>> cp case.scf2up/dn 001_kmesh_emax.scf2up/dn
>>
>> select other direction(s) and repeat the above steps.
>> Compare the band energies listed in the scf2xx files.
>>
>> for the energy:
>> select 001 direction
>> runsp -so -orb -ec 0.000001 -cc 0.000001
>> save 001_kmesh_emax
>>
>> restore non_so
>> do everything again for another direction.
>>
>> Make sure to check EMX and kmesh convergence.
>>
>> PS: I've never done MCA calculations using GGA+U !!
>>
>> Am 05.11.2016 um 06:26 schrieb Rajiv Chouhan:
>>
>>> Dear Dr. P. Blaha,
>>>
>>> I am trying to calculate the magnetic anisotropy energy (MAE) for the
>>> magnetic system Nd-metal. For this I tried couple of methods (energy
>>> theorem and force theorem) to calculate MAE.
>>>
>>> Energy theorem:
>>>
>>> step-1: Performed GGA+U ; Step-2: executed initso_lapw for different
>>> directions 001, 100 etc ; Step-3: Didn't put RLO (relativistic local
>>> orbital in the .inso file)
>>>
>>> Step-4: Performed runsp_lapw -so -orb -dm -ec 0.000001 ; Step-5 Took
>>> the difference of energies E[001] - E[100]
>>>
>>> The above method give correct result in very few cases. Am I doing wrong
>>> somewhere?
>>>
>>>
>>> Force Theorem:
>>>
>>> Will you please explain the steps correctly because I am confused while
>>> doing the steps. I followed the below steps and this is not working for
>>> me.
>>>
>>> Step-1: Performed GGA+U (runsp_lapw -dm -orb -ec 0.000001);
>>>
>>> Step-2: initso_lapw (by taking below actions)
>>>
>>> ---->Add RLO for NONE, ALL, CHOOSE elements? (N/a/c) : N
>>>
>>> Do you have a spinpolarized case (and want to run symmetso) ? (y/N) Y
>>>
>>> Do you want to use the new structure for SO calculations ? (y/N) N
>>>
>>> Step-3: x lapwso -up
>>>
>>> Step-4: x lapw2 -up
>>>
>>> Step-5: x lapw2 -dn
>>>
>>> Step-6: MAE = 001(sum of eigenvalues up & down) - 100(sum of
>>> eigenvalues up & down)
>>>
>>> This force method is also not working properly. Will you please correct
>>> me where I am doing wrong.
>>>
>>> I also followed the following links for my above steps:
>>>
>>> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at
>>> /msg09408.html
>>>
>>> http://zeus.theochem.tuwien.ac.at/pipermail/wien/2010-Septem
>>> ber/013730.html
>>>
>>> Thank you,
>>> R. Chouhan
>>>
>>>
>>> _______________________________________________
>>> Wien mailing list
>>> Wien at zeus.theochem.tuwien.ac.at
>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
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>>> en at zeus.theochem.tuwien.ac.at/index.html
>>>
>>>
>>
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