[DFTB-Plus-User] (no subject)

[veerpal kaur dhiman]

Dear Sir

I have been trying to optimize the geometry of As2S3 with dftb+ for a long
time but i failed. I don't know where is the error? I tried everything .
According to me every thing is correct but perhaps something is misssing or
something is wrong .

    Actually there is the problem of non convergence . I tried by
increasing the temperature but still geometry is hardly converged after a
large no. of steps (1426 steps ) . I also used the large values of k
-points as you said earlier .

   Can you please see that where can be  problem in my input program as
given below :

 Geometry = GenFormat {
5 S
  As S

  1 1  0.2647  0.1917  0.862
  2 1  0.4868  0.3212  0.3607
  3 2  0.4015  0.1213  0.5081
  4 2  0.3474  0.3972  0.0101
  5 2  0.1223  0.2935  0.5590
  0.000 0.000 0.000
  11.474   0    0
    0    9.577   0
    0      0   4.256
}

Driver = ConjugateGradient {
  MovedAtoms = 1:-1
  MaxForceComponent = 1e-4
  MaxSteps =3000
  LatticeOpt = Yes
  FixAngles = Yes
  OutputPrefix = "geom.out"
  AppendGeometries = Yes
ConvergentForcesOnly = No
}

Hamiltonian = DFTB {
  SCC = Yes
  SlaterKosterFiles {
    As-As = "As-As.skf"
    As-S = "As-S.skf"
    S-As = "S-As.skf"
    S-S = "S-S.skf"
  }
  MaxAngularMomentum {
As = "p"
    S = "p"
  }
  Filling = Fermi {
    Temperature [Kelvin] = 300
  }
  KPointsAndWeights = SupercellFolding {
   10 0 0
   0 10 0
   0 0 10
   0.5 0.5 0.5
  }
}

Options{}


ParserOptions {
  ParserVersion = 4
}
    As = "p"
    S = "p"
  }
  Filling = Fermi {
    Temperature [Kelvin] = 300
  }
  KPointsAndWeights = SupercellFolding {
   10 0 0
   0 10 0
   0 0 10
   0.5 0.5 0.5
  }
}

Options{}


ParserOptions {
  ParserVersion = 4
}



and last step of output is as given below:


*******************************************************************************
** Geometry step: 1426, Lattice step: 56
********************************************************************************

  iSCC Total electronic   Diff electronic      SCC error
    1   -0.10889426E+02    0.00000000E+00    0.74952013E-05

 Total Energy:                     -10.8729916742 H
 Total Mermin free energy:         -10.8729916742 H
 Volume:                             0.947545E+03 au^3
 Pressure:                          -0.873620E-08 au    -0.257028E+06 Pa
 Maximal force component:            0.528804E-04
 Maximal Lattice force component:    0.743622E-04 au
>> Charges saved for restart in charges.bin

 Geometry converged



Please give any idea .
Thanking You,

Yours Sincerely,
Veerpal Kaur.
Panjab University,
Chandigarh.
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