[Wien] problems with convergence of SCF for AFM HoPtBi
Xavier Rocquefelte
xavier.rocquefelte at univ-rennes1.fr
Thu Nov 1 11:38:26 CET 2018
I have exactly the same experience. It is really a matter of cooking to
my point of view and strongly depends on the system and what is
happening at the Fermi level.
In my case I am using DFT+U+SOC for such systems. The hubbard term
indeed allows to separate the 4f states. However, the SOC is also
essential and leads to large effects in these systems.
In the case of HoPtBi, all the elements requires SOC. In addition it is
an intermetallic compound, meaning that you have both localized and
delocalized electrons!
Did you try the following procedure:
- DFT+SOC in a self-consistent manner
- DFT+SOC+U on top of the first calculation
Sometimes the lift of degeneracy due to SOC is sufficient to converge
more efficiently DFT+SOC and then after DFT+SOC+U. And sometimes it is
the other way around;)
Best wishes
Xavier
Le 01/11/2018 à 07:19, Fecher, Gerhard a écrit :
> seems to be a more general problem with the rare earth and is related to the 4f electrons,
> I recently tested some pure RE elements (and compounds) and found that similar problems occur in most cases
> sometimes the cycles went smooth, and at a certain point rather everything (from ENE to MMI) started to oscillate in consecutive cycles.
> In some cases it became worth when using larger number of k-points.
>
> Convergence was reached when using TEMP 0.002 and a lower mixing (0.05 or lower)
> and it took long (> 400 cycles) to reach convergence in many cases (ec 0.00001 cc 0.001).
> (but there is still no guarentee, depending on the magnetic state).
>
> As probably all RE (even Lu) need LDA+U or something to heal the 4f problem, it might be helpful in some cases to use +U (about a half Ry) from beginning.
>
> Maybe someone has more experience with the 4f and can share it here.
>
> Ciao
> Gerhard
>
> DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
> "I think the problem, to be quite honest with you,
> is that you have never actually known what the question is."
>
> ====================================
> Dr. Gerhard H. Fecher
> Institut of Inorganic and Analytical Chemistry
> Johannes Gutenberg - University
> 55099 Mainz
> and
> Max Planck Institute for Chemical Physics of Solids
> 01187 Dresden
> ________________________________________
> Von: Wien [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von Laurence Marks [L-marks at northwestern.edu]
> Gesendet: Donnerstag, 1. November 2018 00:13
> An: A Mailing list for WIEN2k users
> Betreff: Re: [Wien] problems with convergence of SCF for AFM HoPtBi
>
> I strongly suggest that you also look at the magnetic moments and what is going on at the Fermi energy and with the 4f. Both :DIS &:ENE are relatively crude tests and often don't tell the whole story.
>
> HDLO can also be important for large RMTs similar to what you have.
>
> Last, but not least, did you use runafm?
>
> _____
> Professor Laurence Marks
> "Research is to see what everybody else has seen, and to think what nobody else has thought", Albert Szent-Gyorgi
> www.numis.northwestern.edu<http://www.numis.northwestern.edu>
>
> On Wed, Oct 31, 2018, 4:10 PM tran at theochem.tuwien.ac.at<mailto:tran at theochem.tuwien.ac.at> <tran at theochem.tuwien.ac.at<mailto:tran at theochem.tuwien.ac.at>> wrote:
> Hi,
>
> Can you show us how :DIS and :ENE are changing (grep them in case.scf).
>
> FT
>
> On Wednesday 2018-10-31 21:35, Kefeng wang wrote:
>
>> Date: Wed, 31 Oct 2018 21:35:38
>> From: Kefeng wang <wangkf80 at gmail.com<mailto:wangkf80 at gmail.com>>
>> Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>>
>> To: wien at zeus.theochem.tuwien.ac.at<mailto:wien at zeus.theochem.tuwien.ac.at>
>> Subject: [Wien] problems with convergence of SCF for AFM HoPtBi
>>
>> Dear all,
>> I am using wien17.1 to perform the DFT calculations for HoPtBi. For the Non-magnetic case, the convergence for the SCF calculation has been achieved using 8000
>> k points while for the AFM case, it is not convergent at all using 4096 k points after 100 iterations. The charge and energy keep fluctuating. However, for
>> GdPtBi with the same lattice structure and AFM order, the corresponding calculations are convergent. I felt very confused. Thanks a lot for your help!
>>
>>
>> The struct file for HoPtBi is shown below:
>>
>> R LATTICE,NONEQUIV.ATOMS: 6 160 R3m
>> MODE OF CALC=RELA unit=bohr
>> 8.860595 8.860595 43.407874 90.000000 90.000000120.000000
>> ATOM -1: X=0.87500000 Y=0.87500000 Z=0.87500000
>> MULT= 1 ISPLIT= 4
>> Pt1 NPT= 781 R0=.000005000 RMT= 2.50000 Z: 78.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -2: X=0.37500000 Y=0.37500000 Z=0.37500000
>> MULT= 1 ISPLIT= 4
>> Pt2 NPT= 781 R0=.000005000 RMT= 2.50000 Z: 78.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -3: X=0.00000000 Y=0.00000000 Z=0.00000000
>> MULT= 1 ISPLIT= 4
>> Ho1 NPT= 781 R0=.000010000 RMT= 2.50000 Z: 67.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -4: X=0.50000000 Y=0.50000000 Z=0.50000000
>> MULT= 1 ISPLIT= 4
>> Ho2 NPT= 781 R0=.000010000 RMT= 2.50000 Z: 67.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0. 0.0000000 0.0000000 1.0000000
>> ATOM -5: X=0.75000000 Y=0.75000000 Z=0.75000000
>> MULT= 1 ISPLIT= 4
>> Bi1 NPT= 781 R0=.000005000 RMT= 2.50000 Z: 83.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> ATOM -6: X=0.25000000 Y=0.25000000 Z=0.25000000
>> MULT= 1 ISPLIT= 4
>> Bi2 NPT= 781 R0=.000005000 RMT= 2.50000 Z: 83.
>> LOCAL ROT MATRIX: 1.0000000 0.0000000 0.0000000
>> 0.0000000 1.0000000 0.0000000
>> 0.0000000 0.0000000 1.0000000
>> 6 NUMBER OF SYMMETRY OPERATIONS
>> 1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 0 0 1 0.00000000
>> 1
>> 0 0 1 0.00000000
>> 1 0 0 0.00000000
>> 0 1 0 0.00000000
>> 2
>> 0 1 0 0.00000000
>> 0 0 1 0.00000000
>> 1 0 0 0.00000000
>> 3
>> 0 1 0 0.00000000
>> 1 0 0 0.00000000
>> 0 0 1 0.00000000
>> 4
>> 1 0 0 0.00000000
>> 0 0 1 0.00000000
>> 0 1 0 0.00000000
>> 5
>> 0 0 1 0.00000000
>> 0 1 0 0.00000000
>> 1 0 0 0.00000000
>> 6
>>
>> Best,
>> Wang
>>
>>
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