[DFTB-Plus-User] Problem with geometry convergence

Bálint Aradi aradi at uni-bremen.de
Fri Dec 20 16:26:54 CET 2019


Dear Alessandro,

The total energy landscape of your molecule is rather flat, our CG
driver has usually difficulties with such scenarious. Using the LBFGS
optimizer as shown in the attached dftb_in.hsd file, I was able to
converge your geometry up to a tolerance of 1e-4 with DFTB+ 19.1.

I left the D3-dispersion as it was, but please note, that the default
damping parameters (as you did not set those explicitely) require DFTB3
(3rd order and XH-damping) and the 3ob SK-set! They are not considered
in the attached example as I wanted to introduce as few changes as
possible. Nevertheless, make sure you change it accordingly for any
serious production calculations.

  Best regards,

  Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/

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Geometry = GenFormat {
<<< "C10DNBDT_Mercury.gen"
}
Driver = ConjugateGradient {
  MovedAtoms = 1:-1 
  #MaxForceComponent = 1.00E-8  # Extremely small!
  MaxForceComponent = 1.E-4  # Extremely small!
  MaxSteps = 10000
  OutputPrefix = "geom"
  LatticeOpt = No
}
Hamiltonian = DFTB {
  SCC = Yes
  #SCCTolerance = 1.0E-010
  SCCTolerance = 1.0E-5  
  MaxSCCIterations = 10000  
 Dispersion = DftD3 {}
 Mixer = Broyden {
   #MixingParameter = 0.99
   MixingParameter = 0.2
 }
  Filling = Fermi {
     Temperature [Kelvin] = 300.0
  }
  KpointsAndWeights = SuperCellFolding {
    4 0 0
    0 4 0
    0 0 4
    0.0 0.0 0.0
  }
  MaxAngularMomentum = {
    S = "d"
    C = "p"
    H = "s"
  }
  SlaterKosterFiles = Type2FileNames{
    Prefix = "/home/aradi/research/slakos/official/mio/mio-1-1/" #If it is in a different directory, put the path
    Separator = "-"
    Suffix = ".skf"
  }
}
#Analysis = {
#WriteEigenvectors=Yes
#EigenvectorsAsTxt=Yes
#}

Parallel {
  # Allow OMP threads explicitely to test for hybrid parallelisation with
  # MPI-binary. (Check the manual before using this in production runs!)
  UseOmpThreads = Yes
}

ParserOptions = {
  ParserVersion = 5
}




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