[DFTB-Plus-User] (no subject)

[veerpal kaur dhiman]

Dear sir,

i have done lattice optimization of As2S3 with following program :

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 = 500
  LatticeOpt = Yes
  FixAngles = Yes
  OutputPrefix = "geom.out"
}

Hamiltonian = DFTB {
  SCC = No
  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] = 0
  }
  KPointsAndWeights = SupercellFolding {
   1 0 0
   0 1 0
   0 0 2
   0.5 0.5  0.5
  }
}

Options {}

ParserOptions {
  ParserVersion = 4
}



and i got the optimized coordinates in the "geom.out" file as given below :
    5
** Geometry step: 309, Lattice step: 10
   As     -0.20642746     -0.34931126      1.07003390
   As      2.55293747      0.33664524     -0.66736509
    S      2.04306238     -1.10134525      1.07003321
    S      0.33058893      1.07743972     -0.66736081
    S     -3.09805050      1.36105109      1.07240009


which are quite different from the given coorinates in the starting of the
program .
I learnt that the optimized coordinated should not much differ from the
original coordinates . Also the structure made in vesta with optimized
coorinates is wrong while that made with the given coordinates is correct.

My questions are:
1. Is my program is correct or not?
2. Is it necessary to give LatticeOpt=Yes and FixAngles =Yes in driver of
the program?
3. Is it correct to give SCC= No?
4. Are the  given k points correct?


Kindly give me any ideas .

Thanks a lot

Veerpal Kaur
Panjab University
Chandigarh.
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