[Wien] ghost band

Tue Feb 27 14:46:14 CET 2007

Two other things:
1) Use -in1new once :DIS has reduced down to a reasonable value, e.g. 0.01.
2) Do a grep :PLA case.scf . Using a mixing factor of 0.01 or 0.005 is
in most cases meaningless and is not going to make any difference.

See, for instance,
http://zeus.theochem.tuwien.ac.at/pipermail/wien/2005-May/005277.html
or similar.

N.B., we need a FAQ about how to set the mixing parameters right
and/or what to do in problem cases.

On 2/27/07, Stefaan Cottenier <Stefaan.Cottenier at fys.kuleuven.be> wrote:
> Do 'grep :DIS case.scf' to see how the charge distance evolves. Is is
> steadily decreasing or oscillating? Assuming the former, it looks like
> you do not have a real problem, but are using a (somewhat older?) wien
> version with the maximum number of iterations by default at 20. If after
> those 20 iterations your -fc 1 force criterium is not satisfied, you
> thet this message. In that case, just add -i 999 (a crazy high number of
> iterations). The risk is now of course that it will run 'forever' if it
> refuses to converge. Watch it closely...
>
> Stefaan
>
> >Dear Stefaan,
> >
> >Thank you very much for your prompt reply and advice.
> >I have restarted the initialization from a scratch directory. The SCF
> >iteration stopped at cycle 9 after lapw1. Again, all the error files
> >were empty. The case.scf2 file shown message: QTL-B value EQ 5.59310 in
> >band of energy  -0.55906 atom = 12, L=1. The fermi level was 0.10020
> >I tried to remove the broyden file, changed all global E-parameter from
> >-0.04 to -0.10, and changed E-parameter for atom 12, L=1 from 0.3 to
> >-0.5 in case.in1c file. The SCF iteration then was stopped at cycle 20
> >with the message "Forces not converged". The ghost band message still
> >exist but apparently, the value was reduced to 3.246 for atom 2.
> >I tried to decrease the mixing factor in case.inm file from 0.01 to
> >0.005 and restarted the SCF iteration. But the same problem occurred,
> >where the iteration stop at cycle 20 with message "Forces not
> >converged". (The issued command was: run_lapw -p -fc 1 NI)
> >I don't have experience to solve the scf converged problem. Any
> >suggestion? Should I ignore the ghost band message since the qtl value
> >was quite small?
> >
> >Thanks in advance
> >
> >Regards
> >Yen Fun
> >
> >
> >Stefaan Cottenier wrote:
> >
> >
> >>>, I don't understand why LO is added in case.in1 file (in what case we
> >>>should add the LO), and how to define the energy for this LO. Can
> >>>anyone explain to me?
> >>>
> >>>
> >>>
> >>Most of the LO's are decided upon automatically, and this is fairly
> >>robust. What you probably refer to is adding extra LO's at high
> >>energies. This is needed when you are interested in the DOS of
> >>unoccupied states. This enhances precision, but is rarely necessary to
> >>get a case converged. I don't think your troubles are due to this.
> >>
> >>
> >>
> >>
> >>>Currently I tried to run an interface LiTaO3/RuO2. Everything was fine
> >>>during initialization. When come to scf calculation, the dayfile
> >>>message shown: /INFO: K-LIST in CLMSUM changed in MIXER xxx /after
> >>>Lapw1,and QTL-B value shown after Lapw2.The calculation was then stop
> >>>with message "lapw2 crashed!" at cycle 2. In this case I used RmtKmax
> >>>5 with Kmesh 50. I understand that we can ignore the K-list message in
> >>>cycle 1. So I presume that the ghostband have caused the problem
> >>>(QTL-B value >5%). Thus, I tried to change all E-parameter from 0.3 Ry
> >>>to -0.04 Ry, which is 0.2 Ry below the Fermi Level and rerun the scf.
> >>>But it doesn't help. The same error occurred again.
> >>>
> >>>
> >>>
> >>Re-initialize from scratch in a new, clean directory to make sure that
> >>this k-list message is really there. It could be a result of messing up
> >>something while playing with the initialization. If it still crashes
> >>after lapw2, look at the bottom of case.scf2 to see which state triggers
> >>the qtl-b problem. You will also see there to what value you have the
> >>change the linearization energy of that state.
> >>
> >>
> >>
> >>
> >>>I tried to switch "in1new 5", but this time the calculation even stop
> >>>at 1^st cycle. Then I tried to reduce the mixing factor from 0.1 to
> >>>0.01, with restart the dstart. The calculation then stopped at cycle 4
> >>>after LAPW1, with empty error file.
> >>>
> >>>
> >>>
> >>I assume you are making all these changes in the same directory? If you
> >>do not know exactly what you are doing, it's easy to mess things up. For
> >>such a big interface supercell, I would definitely start with a mixing
> >>value around 0.01. Try it, in a clean directory. If there is really no
> >>error message, look in case.dayfile and to your 'screen' output to find
> >>out why it stopped (queue problem?)
> >>
> >>
> >>
> >>
> >>>Another thing I want to note here is I found that there is no core for
> >>>Lithium, where from case.scfc file, I noticed that the core for
> >>>Lithium is 0.0000Ry. I am not sure whether this is the cause for the
> >>>problem or not. Did anyone face the same problem before?
> >>>
> >>>
> >>>
> >>That is no problem. The 1s level of Li is at -3.8 Ry, the 2s is at -0.2
> >>Ry. With the default separation energy of -6 Ry, both fall in the
> >>valence region. There are no core states for Li.
> >>
> >>Stefaan
> >>
> >>
> >>Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
> >>
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> >>
> >>
> >>
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-- 
Laurence Marks
Department of Materials Science and Engineering
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