[DFTB-Plus-User] Dispersion model (SlaterKirkwood)

[张超]

Dear all,

I want to calculate the dynamics process of the Muti-walled carbon nanotubes.
So, the dispersion block is used to empirically correct the DFTB interactions for van der Waals interactions.

The SlaterKirkwood dispersion model is implemented in my calculation, but i do not know whether the code is right,
especially the CovalentRadius of the carbon.
Below is my input file.

Besides, in the user manual (page 34) of version 1.2 (DFTB+), it says that if atoms are able to move during your 
calculation (geometry relaxation or molecular dynamics) you should always check whether the coordination of your 
atoms has changed during the run. what does it mean?

Geometry = GenFormat {
  <<< "geom.gen"
}
Driver = VelocityVerlet {
  MovedAtoms = 1:-1
  Steps = 10000
  KeepStationary = Yes
  TimeStep [fs] = 0.1
  OutputPrefix = "geom.out"
  Thermostat = None {}
  Velocities [AA/ps] = {                
   <<< "velocity.txt"
   }
   ConvergentForcesOnly = Yes 
}
Hamiltonian = DFTB {
  SCC = Yes
  SCCTolerance = 1.0e-5
  MaxSCCIterations = 10000
  OrbitalResolvedSCC = Yes
  Mixer = Broyden {
    MixingParameter = 0.2
    CachedIterations = -1
    InverseJacobiWeight = 1.000000000000000E-002
    MinimalWeight = 1.00000000000000
    MaximalWeight = 100000.000000000
    WeightFactor = 1.000000000000000E-002
  }
  MaxAngularMomentum = {
    C = "p"
  }
  SpinPolarisation = {}
  Eigensolver = RelativelyRobust{}
  Filling = Fermi {
    Temperature [Kelvin] = 1000.0
  }
  SlaterKosterFiles = {
    C-C = "C-C.skf"
  }
  KPointsAndWeights = {
  0.0 0.0 0.0 1.0
  }
  OldSKInterpolation = No
  OldRepulsiveSum = No                        
  ReadInitialCharges = No
  Dispersion = SlaterKirkwood{
 PolarRadiusCharge =HybridDependentPol{
  C={
    CovalentRadius[Angstrom]=0.8
    HybridPolarisations [Angstrom^3, Angstrom,]={
    1.382 1.382 1.382 1.064 1.064 1.064 3.8 3.8 3.8 3.8 3.8 3.8 2.5
}
} 
}
}                  
}
Options = {
  WriteDetailedOut = Yes
  WriteBandOut = Yes
}
ParserOptions = {
  ParserVersion = 4
  StopAfterParsing = Yes
}

Thank you
chao


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