[Wien] Problems in convergence due to application of mBj potential
Peter Blaha
pblaha at theochem.tuwien.ac.at
Thu Aug 30 15:48:33 CEST 2012
Once again:
Do you mean MSR1 or MSR1a ???? The little "a" makes a big difference
and you can only compare PRATT and MSR1 for mBJ, but not MSR1a.
Of course, a second try could be to use MSR1a and mBJ (without SO) and
check how much the structure changes.
> performance of MRS1a and PRATT when using mBJ in the band structure
> calculation (as described in section 4.5.9 of the WIEN_12 Users
> Guide). So, I was trying to improve the band gap and spin splittings
> of the system (not to relax it) with mBJ, this is the reason why I
> switched the -so option in this calculation (but not in the previous
> structure optimization for the reasons you described).
> Now, I know that MSR1a try to optimize the structure, what means it
> is not an ordinary SCF cycle, so SOC is an unappropriated option as
> you posted. I am sorry for the misunderstanding.
> I will try a new structure optimization using MSR1a-mBJ with the
> same parameters employed in the MSEC1-PBE case, allowing a fair
> comparison between their performances. I promise to report the result
> as soon as possible.
> Thank you for your attention,
> Luis
>
>
>
> 2012/8/30 Peter Blaha <pblaha at theochem.tuwien.ac.at>:
>> For sure, forces are NOT ok when you switch on spin-orbit coupling.
>>
>> But please: think about the physics: InP is not that heavy and is a
>> semiconductor. You do NOT need SO for any structural relaxation as
>> it has negligible effects anyway.
>> (However, you may NEED SO for bandstructure properties, effective
>> masses,....,
>> but calculate this afterwards with fixed positions, NEVER with MSR1a but
>> with MSR1).
>>
>>
>> Furthermore, in your mail it sounds as if you mixed up various schemes
>> with WIEN2k.
>>
>> When using MSR1 you do NOT optimize positions (only "electrons"),
>> MSR1a you ALWAYS will optimize positions (in fact, when you do
>> not
>> have case.inM, it will be generated automatically !)
>>
>> And for both schemes you use the command run_lapw !
>>
>> Alternatively, you can use min_lapw (and MSR1, not MSR1a), which will
>> also optimize positions (and if case.inM does not exist, will generate
>> it automatically).
>>
>> Both, MSR1a or min_lapw accept "constraint positions", when you execute
>> x pairhess -copy (creates case.inM)
>> edit case.inM and set some values to zero for constraining them.
>> x pairhess -copy (so that the constrains are honored in the hessian for
>> PORT).
>>
>> PS: At least for insulators (but usually even for difficult 3d-metallic
>> systems)
>> I strongly recommend MSR1a over min_lapw, as it is almost always much
>> faster and more stable. The only problem left is to determine a unique way
>> when to stop MSR1a (this means: what stopping criteria one should use),
>> but when you accept some remaining forces (less than 5 mRy/bohr),
>> even this is not a serious problem and default criteria (or even a bit
>> larger value than 2.0 in case.inM) are sufficient and reasonable.
>>
>> PPS: When one tries MSR1a together with mBJ, I'd first converge mBJ (at
>> least
>> partly) with MSR1 (or PRATT and later on MSR1), and then remove case.in0_grr
>> (this will fix the value of "c" in mBJ and make things for MSR1a more
>> stable).
>>
>>
>> Am 29.08.2012 19:03, schrieb Luis Carlos Ogando Dacal:
>>
>>> Dear Prof. Laurence Marks,
>>>
>>> Let me answer you using your previous message.
>>>
>>>> First, a reminder. Using MSR1a with mBJ is a computational experiment.
>>>> It may not give reasonable results, or it might -- I do not know and I
>>>> am not sure that anyone does, yet. The "standard" method is not to
>>>> vary the atomic positions with mBJ, but this may not be optimal.
>>>
>>>
>>> Yes, I know. I just tested MSR1a as you asked the WIEN mailing list
>>> in a message you sent in August, 22. I will keep on the calculation
>>> using the standard and reliable methods. My report was just a little
>>> contribution to your efforts.
>>>
>>>> One thing to check, in your case what are the positions like in the
>>>> substrate? Assuming that you have made this thick enough (e.g. 20 au
>>>> or more) in the center the positions should be close to those with PBE
>>>> and/or the bulk. If they are wildly different this implies that the
>>>> bulk lattice parameters for PBE do not match well those from mBJ. (Of
>>>> course, if you have only used 2 layers or so of substrate you cannot
>>>> test this.)
>>>
>>>
>>> Actually, I did not optimized the structure using MSR1a. I did it
>>> in a previous calculation with MSEC1 and PBE with case.inM fixing the
>>> substrate positions. Only after that, I used mBJ to improve the gap.
>>> When I employed mBJ with PRATT (0.2 followed by 0.4 mixing factors) I
>>> got the convergence in the SCF cycle and a smooth decrease in ETEST.
>>> In the MSR1a test, I noticed abrupt changes in ETEST and after the
>>> last iteration I got the message "energy in SCF NOT CONVERGED".
>>> As I was not optimizing the structure when using MSR1a, I had not a
>>> case.inM file and all the atoms changed position during MSR1a
>>> calculations. Despite the fact that I used a thin substrate (I will
>>> improve this in a next step), the atomic positions changed only by a
>>> factor of 10^(-3) when compared to the previously PBE relaxed
>>> structure (It is important to remember that MSR1a did not converged
>>> and I used the last generated case.struct to compare with PBE relaxed
>>> structure)
>>>
>>>> When you say "it did not converge with MSR1a", what exactly do you
>>>> mean? It may be better to send the case.struct and case.scf files to
>>>> my email directly.
>>>
>>>
>>> I was talking about the message at the end of the MSR1a calculation
>>> ("energy in SCF NOT CONVERGED"). I have not calculated any physical
>>> property of the system.
>>> I will send you the files in another message.
>>>
>>>> If you fix some atoms in case.inM, then the ones which are not fixed
>>>> will move. While some people argue that this is OK, I have
>>>> reservations. If you fix all the atoms in case.inM then MSR1a will
>>>> crash on you -- you have to use MSR1 (or MSEC3).
>>>
>>>
>>> All the best,
>>> Luis
>>>
>>>
>>>
>>>> On Wed, Aug 29, 2012 at 7:50 AM, Luis Carlos Ogando Dacal
>>>> <ogando at ieav.cta.br> wrote:
>>>>>
>>>>> Dear Prof. Laurence Marks (and WIEN2k users),
>>>>>
>>>>> I would like to report my recent experience in using MSR1a with
>>>>> mBJ. I have a semiconductor system composed by In and P atoms that I
>>>>> relaxed using PBE. After that, I tried the mBJ SCF cycle using PRATT
>>>>> as recommended in section 4.5.9 of the WIEN Users Guide. I got the
>>>>> convergence after a long cycle (strict convergence criteria), but no
>>>>> convergence was obtained with MSR1a.
>>>>> If you want any detail of my system and/or calculation, just send
>>>>> me an e-mail.
>>>>> Another point, my system tries to simulate a substrate and a cap
>>>>> stressed layer. As a consequence, I need to fix the substrate atoms
>>>>> during the SCF cycles. I would like to know if this can be done with
>>>>> case.inM when using MSR1a (or any other way). I believe that fixing
>>>>> atoms leads MSR1a to behave like MSR1. Is this right ?
>>>>> All the best,
>>>>> Luis Ogando
>>>>>
>>>>>
>>>>>
>>>>> 2012/8/22 Laurence Marks <L-marks at northwestern.edu>:
>>>>>>
>>>>>> I am sure Peter had a typo - I think he meant MSR1 not MSR1a. Whether
>>>>>> MSR1a
>>>>>> is a good idea with mBJ is currently unclear; there was a recent
>>>>>> discussion
>>>>>> of this, look in the email archives.
>>>>>>
>>>>>> A good topic where readers of this list could contribute is testing
>>>>>> whether
>>>>>> MSR1a with mBJ is physically reasonable and reporting back.
>>>>>>
>>>>>> On Aug 22, 2012 8:47 AM, "Madhav Ghimire" <ghimire.mpg at gmail.com>
>>>>>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> Dear Prof. Marks,
>>>>>>> Thank you very much for replying immediately. I was just replying
>>>>>>> to
>>>>>>> your post.
>>>>>>> As in userguide of wien2k, it is suggested to edit the case.inm and
>>>>>>> change
>>>>>>> MSR1a with PRATT as MSR1a leads to convergence problems in mBj. Hence,
>>>>>>> I
>>>>>>> performed the calculations by changing MSR1a with PRATT.
>>>>>>> I will follow to what you suggest right now and report within a day or
>>>>>>> two.
>>>>>>> Please let me know more if I have to be cautious somewhere in the
>>>>>>> calculations.
>>>>>>> Thanks.
>>>>>>> Madhav
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On Wed, Aug 22, 2012 at 8:21 PM, Laurence Marks
>>>>>>> <L-marks at northwestern.edu>
>>>>>>> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Can you send the case.scf file to me directly? I am curious why MSR1
>>>>>>>> does
>>>>>>>> not converge well for some mBJ and there are some things printed in
>>>>>>>> case.scfm which may explain.
>>>>>>>>
>>>>>>>> ---------------------------
>>>>>>>> Professor Laurence Marks
>>>>>>>> Department of Materials Science and Engineering
>>>>>>>> Northwestern University
>>>>>>>> www.numis.northwestern.edu 1-847-491-3996
>>>>>>>> "Research is to see what everybody else has seen, and to think what
>>>>>>>> nobody else has thought"
>>>>>>>> Albert Szent-Gyorgi
>>>>>>>>
>>>>>>>> On Aug 21, 2012 9:50 PM, "Madhav Ghimire" <ghimire.mpg at gmail.com>
>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Dear wien users and developers,
>>>>>>>>> I am working on some 3d TM oxides. With a normal scf cycle
>>>>>>>>> with or
>>>>>>>>> without inclusion of U value, I got good convergence in energy and
>>>>>>>>> charge.
>>>>>>>>> This oxide material is reported to have a bandgap of approx. 0.3 eV.
>>>>>>>>> In GGA,
>>>>>>>>> I do not observe any gap. In the meantime even with very high value
>>>>>>>>> of U,
>>>>>>>>> the bandgap do not open up. Because of this, I tried to implement
>>>>>>>>> mBj
>>>>>>>>> potential (in order to find the bandgap) both with and without
>>>>>>>>> inclusion of
>>>>>>>>> U, but the energy and charge do not converge.
>>>>>>>>> Rather even for a large number of iteration (199), the energy and
>>>>>>>>> charge
>>>>>>>>> remains constant without convergence (shown below).
>>>>>>>>>
>>>>>>>>> For GGA without mBj the scf cycle smoothly converges as below:
>>>>>>>>> in cycle 22 ETEST: .0000236850000000 CTEST: .0038743
>>>>>>>>> in cycle 23 ETEST: .0000184300000000 CTEST: .0012996
>>>>>>>>> in cycle 24 ETEST: .0000174650000000 CTEST: .0006011
>>>>>>>>> in cycle 25 ETEST: .0000037600000000 CTEST: .0007451
>>>>>>>>> in cycle 26 ETEST: .0000016050000000 CTEST: .0001163
>>>>>>>>>
>>>>>>>>>> stop
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> while with mBj+GGA, energy and charge convergence remains constant
>>>>>>>>> above cycle 103 and could not converge as below:
>>>>>>>>> in cycle 193 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 194 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 195 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 196 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 197 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 198 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>> in cycle 199 ETEST: .2112103950000000 CTEST: 2.0591251
>>>>>>>>>
>>>>>>>>>> energy in SCF NOT CONVERGED
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Does anyone have experienced this type of problems. If so, please
>>>>>>>>> let me
>>>>>>>>> know how it can be converged. I followed all the steps as described
>>>>>>>>> in
>>>>>>>>> previous wien mail and userguid but could not solve.
>>>>>>>>> Your help to solve this issue will be higly appreciated.
>>>>>>>>> Thanks in advance
>>>>>>>>>
>>>>>>>>> Madhav Ghimire
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> MANA, National Institute for Materials Science (NIMS)
>>>>>>>>> 1-1 Namiki, Tsukuba, Ibaraki, Japan
>>>>>>>>> Phone: +81-29-851-3354 (ex.4115)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Wien mailing list
>>>>>>>>> Wien at zeus.theochem.tuwien.ac.at
>>>>>>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> MANA, National Institute for Materials Science (NIMS)
>>>>>>>>> 1-1 Namiki, Tsukuba, Ibaraki, Japan
>>>>>>>>> Phone: +81-29-851-3354 (ex.4115)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>> _______________________________________________
>>>>>>>> Wien mailing list
>>>>>>>> Wien at zeus.theochem.tuwien.ac.at
>>>>>>>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> MANA, National Institute for Materials Science (NIMS)
>>>>>>> 1-1 Namiki, Tsukuba, Ibaraki, Japan
>>>>>>> Phone: +81-29-851-3354 (ex.4115)
>>>>>>>
>>>>>>>
>>>>>>
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>>>>>> Wien mailing list
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>>>>>>
>>>>> _______________________________________________
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>>>>
>>>>
>>>>
>>>>
>>>> --
>>>> Professor Laurence Marks
>>>> Department of Materials Science and Engineering
>>>> Northwestern University
>>>> www.numis.northwestern.edu 1-847-491-3996
>>>> "Research is to see what everybody else has seen, and to think what
>>>> nobody else has thought"
>>>> Albert Szent-Gyorgi
>>>> _______________________________________________
>>>> Wien mailing list
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>>>
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>>
>> --
>>
>> P.Blaha
>> --------------------------------------------------------------------------
>> 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 WWW:
>> http://info.tuwien.ac.at/theochem/
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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 WWW: http://info.tuwien.ac.at/theochem/
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