[Wien] Charge convergence

[Laurence Marks]

tail -n 200000 *.scf $1 | grep -e :ADIST -e :DIR -e :MV -e GREED -e
:FRMS -e :ENE -e :CHARG -e PRATT \
-e :DIS -e "MIXING SC" -e ":RANK" -e PLANE | \
grep -v -e "with 1.0" -e scheme -e CONTRIBUTION | \
tail -n 50

On Tue, Jul 11, 2017 at 1:20 PM, Luis Ogando <lcodacal at gmail.com> wrote:
> Dear Prof. Marks,
>
>    Thank you very much for your explanation.
>    Unfortunatelly, I am stil using Wien2k 14.2, without the "Check" command.
>    Anyway, I can wait for the charge convergence (for a while). If it takes
> too long and nothing bad happens, I will "kill" the optimization.
>    Thank you again.
>                 All the best,
>                              Luis
>
>
> 2017-07-11 13:13 GMT-03:00 Laurence Marks <L-marks at northwestern.edu>:
>>
>> It is possible for :ENE (Energy, -ec) to seem to converge, but has not
>> -- so it is always wise IMO to also use the charge converge (:DIS,
>> -cc). A value of .0004130 is probably OK, I suggest using the "Check"
>> command which gives more information. (Peter added it to version 16,
>> presumably 17 as well as a command Check-mixing.)
>>
>> From the variational principle, the density converges more slowly than
>> the energy. Depending upon what you are trying to do your charge
>> convergence may be fine. For something like phonons it probably is
>> not. I will note that very good charge convergence often requires good
>> k-mesh, RKMAX etc, more than is needed for a routine calculation.
>>
>> N.B., with more atoms charge convergence can be harder to achieve --
>> and less important.
>>
>> On Tue, Jul 11, 2017 at 9:40 AM, Luis Ogando <lcodacal at gmail.com> wrote:
>> > Dear Prof. Marks and Wien2k community,
>> >
>> >    Good afternoon !
>> >    Just a curiosity about the charge convergence criteria. I am
>> > optimizing a
>> > supercell and the charge convergence limit I am using is 0.001. The same
>> > numerical value for the energy convergence.
>> >    The energy is finally converged, but the charge is not despite the
>> > fact
>> > that its change is below the limit in the last 10 iterations.
>> >
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  1 0.001 -.0002028
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0006007
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  1 0.001 -.0002590
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0007240
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0008640
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0005344
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0005217
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0002525
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0004560
>> > CarbazoleLDAopt.dayfile::CHARGE convergence:  0 0.001 .0004130
>> >
>> >    If I am not wrong, the convergence is achieved after 3 consecutive
>> > iterations with changes below the limit, but in my case this is
>> > happening
>> > for more than 10 iterations  without convergence.
>> >    Could you please kindly explain what may be happening ?
>> >    Thank you !
>> >                     Luis
>> >
>>
>>
>>
>> --
>> 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 ; Corrosion in 4D:
>> MURI4D.numis.northwestern.edu
>> Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
>> Co-Editor, Acta Cryst A
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>
>



-- 
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 ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A