[DFTB-Plus-User] SCC does not converge.
Dawid Grabarek
dawid.grabarek at pwr.edu.pl
Thu Feb 18 20:42:41 CET 2016
Dear Nir,
I forgot that by default temperature is given in energy units... .
Now when I use
Temperature [K] = 300.0
everything seems fine.
Regards,
Dawid Grabarek
----- oryginalna wiadomość -----
od: "Goldman, Nir" <goldman14 at llnl.gov>
data: czwartek, luty 18, 2016 20:33
temat: Re: [DFTB-Plus-User] SCC does not converge.
do: User list for DFTB+ related questions <dftb-plus-user at mailman.zfn.uni-bremen.de>
|
> Dear Dawid,> >
> I was able to run a number of geometry optimization steps on the larger system you sent earlier (chromo-0.5.gen) by including the following in your input file:> >
> Filling = Fermi {
> Temperature [Kelvin] = 300.0
> }
>
> I also changed the SCC convergence to 1e-6, which likely helped speed things up.
>
> Setting the electronic temperature to a non-zero value allows for the Mermin functional to be calculated, which essentially “smears" the electrons to excited states by computing fractional occupancies for the system according to the Fermi-Dirac distribution. This can effect can be very important to systems with molecular ions, for example, which can exhibit thermal electronic excitations even at relatively low temperature.
>
> Hope that helps,
>
> Nir
> >
> > From: <dftb-plus-user-bounces at mailman.zfn.uni-bremen.de> on behalf of Dawid Grabarek <dawid.grabarek at pwr.edu.pl>
> Reply-To: User list for DFTB+ related questions <dftb-plus-user at mailman.zfn.uni-bremen.de>
> Date: Thursday, February 18, 2016 at 10:43 AM
> To: User list for DFTB+ related questions <dftb-plus-user at mailman.zfn.uni-bremen.de>
> Subject: Re: [DFTB-Plus-User] SCC does not converge.
> >
> > > Dear Ben,
>
> Unfortunately, my happiness came too early... . As the optimization proceeds
> my system blows up. All bonds break down and atoms just fly into space... .
> I have noticed that all oxygen and sulfur atoms get charges equal ca. +1.5
> for the "optimized" structure. In fact, the breakdown of all of my systems
> begins just after first optimization step. What would you suggest?
> Different initial charges?
>
> Best regards,
> Dawid Grabarek
>
> ----- oryginalna wiadomość -----
> od: Ben Hourahine <benjamin.hourahine at strath.ac.uk>
> data: czwartek, luty 18, 2016 16:29
> temat: Re: [DFTB-Plus-User] SCC does not converge.
> do: dftb-plus-user at mailman.zfn.uni-bremen.de
>
-----------------------------------------------------------
> _______________________________________________> > DFTB-Plus-User mailing list> > DFTB-Plus-User at mailman.zfn.uni-bremen.de> > https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-> > plus-user> > -------> Dawid Grabarek, M.Sc.> Wroclaw University of Technology> Faculty of Chemistry> Advanced Materials Modelling and Engineering Group> >
> > > >
> > -- > Nir Goldman > Material Sciences Division, PLS > Lawrence Livermore National Laboratory > P.O. Box 808, L-288 > Livermore, CA 94551-0808 > Phone: (925) 422-3994 > Fax: (925) 422-2382 > https://pls.llnl.gov/people/staff-bios/msd/goldman-n |-----------------------------------------------------------
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> DFTB-Plus-User at mailman.zfn.uni-bremen.de
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> plus-user
-------
Dawid Grabarek, M.Sc.
Wroclaw University of Technology
Faculty of Chemistry
Advanced Materials Modelling and Engineering Group-----------------------------------------------------------
|
> > Hello Dawid,
> >
> > have you tried a finite electronic temperature (this can really help with self consistency)?
> > The attached example was at 0 Kelvin, I'd suggest something like room temperature as a first test.
> >
> > Also the SCC tollerance you are using is quite small (try the default value, unless there is a good reason otherwise).
> >
> > Regards
> >
> > Ben
> >
> > > > On 07/02/16 21:11, Dawid Grabarek wrote:
> > Dear DFTB+ Experts,
> >
> > I want to perform geometry optimization of a system consisting of increasing
> > number of amino acid residues.
> > I have managed to successfully perform optimization for system up to
> > 1870 atoms, using non-SCC DFTB approach.
> > However when I want to use SCC-DFTB3 for system larger than 460 atoms,
> > the charges do not converge even after a few thousand iterations. The iteration
> > does not proceed in fact.
> > I attach part of my output file:
> >
> > 9976 -0.21529827E+03 -0.13123659E+02 0.53106709E+01
> > 9977 -0.17459612E+03 0.40702148E+02 0.53210677E+01
> > 9978 -0.20103686E+03 -0.26440744E+02 0.53230816E+01
> > 9979 -0.24096058E+03 -0.39923717E+02 0.53269557E+01
> > 9980 -0.19704089E+03 0.43919692E+02 0.53385778E+01
> > 9981 -0.21818849E+03 -0.21147597E+02 0.53345550E+01
> > 9982 -0.25301554E+03 -0.34827052E+02 0.53358740E+01
> > 9983 -0.27482831E+03 -0.21812768E+02 0.53316452E+01
> > 9984 -0.29608303E+03 -0.21254728E+02 0.53454981E+01
> > 9985 -0.26626843E+03 0.29814602E+02 0.53557124E+01
> > 9986 -0.29473653E+03 -0.28468098E+02 0.53569507E+01
> > 9987 -0.25516950E+03 0.39567029E+02 0.53763278E+01
> > 9988 -0.28536057E+03 -0.30191072E+02 0.53798582E+01
> > 9989 -0.28895556E+03 -0.35949882E+01 0.53806192E+01
> > 9990 -0.22896112E+03 0.59994443E+02 0.53836906E+01
> > 9991 -0.22485550E+03 0.41056157E+01 0.53812648E+01
> > 9992 -0.22164301E+03 0.32124948E+01 0.53759401E+01
> > 9993 -0.16929036E+03 0.52352651E+02 0.53873225E+01
> > 9994 -0.19352833E+03 -0.24237970E+02 0.53825003E+01
> > 9995 -0.16294863E+03 0.30579698E+02 0.53834931E+01
> > 9996 -0.11288863E+03 0.50060003E+02 0.53970748E+01
> > 9997 -0.10136437E+03 0.11524262E+02 0.53984882E+01
> > 9998 -0.10537121E+03 -0.40068449E+01 0.53984460E+01
> > 9999 -0.84099319E+02 0.21271891E+02 0.53857706E+01
> > 10000 -0.76159647E+02 0.79396717E+01 0.53785016E+01
> >
> > Total Energy: -66.7997002259 H
> > Total Mermin free energy: -66.7997002259 H
> > ERROR!
> > -> SCC is NOT converged, maximal SCC iterations exceeded
> >
> > I know that going up to 10 000 is crazy but just wanted to see what will happen.
> >
> > Anyway, I also attach two input files for systems for which I cannot
> > reach the SCC convergence. What is more I also attach a PDF file which contains
> > various parameters combination that I used to check whether changing
> > parameters and Mixer will allow to reach convergence.
> > I did that based on what I read in paper by V. Eyert (Journal of
> > Computational Physics, 124, 271-285, 1996).
> >
> > Best wishes,
> >
> > Dawid Grabarek
> >
> >
> >
> > -------
> > Dawid Grabarek, M.Sc.
> > Wroclaw University of Technology
> > Faculty of Chemistry
> > Advanced Materials Modelling and Engineering Group
> >
> >
> > _______________________________________________ > DFTB-Plus-User mailing list > DFTB-Plus-User at mailman.zfn.uni-bremen.de https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user > > -- > Dr. B. Hourahine, SUPA, Department of Physics, > University of Strathclyde, John Anderson Building, > 107 Rottenrow, Glasgow G4 0NG, UK. > +44 141 548 2325, benjamin.hourahine at strath.ac.uk > > 2013/4 THE Awards Entrepreneurial University of the Year > 2012/13 THE Awards UK University of the Year > > The University of Strathclyde is a charitable body, > registered in Scotland, number SC015263 | -----------------------------------------------------------
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