[DFTB-Plus-User] Wurtzite ZnO surface structure relaxtion problem

[LuShaohua]

Dear Dr. Bálint Aradi

My interest is surface reconstructions of crystals. We have used DFTB+ in finding the surface structure of covalent crystal surfaces (e.g. silicon and diamond),  DFTB+ gives very good results compare to DFT. 
Recently we moved from covalent crystal surface to ionic, and encountered the following problem while we try to relax polar surface configurations: 

ERROR!
-> SCC is NOT converged, maximal SCC iterations exceeded

ps. I used znorg-0-1 skf files in the calculations. 
Two input files have been attached below. 

Best 
Shaohua
Ph.D candidate
Jilin University, Changchun, China


dftb_in.hsd
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Geometry = GenFormat {
 <<<"dftb.gen"
}

Driver = ConjugateGradient {
  ####
  MovedAtoms = { 1 2 3 4 5 6 7 8 25 26 27 28 29 30 31 32 }
  ####
  MaxForceComponent = 1E-3
  MaxSteps = 1000
  OutputPrefix = "geom.out"
}

Hamiltonian = DFTB {
  SCC = Yes
  MaxSCCIterations = 300
  SCCTolerance= 1E-4
  SlaterKosterFiles = Type2FileNames {
    Prefix = "./"
    Separator = "-"
    Suffix = ".skf"
    LowerCaseTypeName = No
  }


  ####
  MaxAngularMomentum {
    O = p
    Zn = d
  }
  ####

  Mixer = Broyden {
    MixingParameter = 0.3
  }
  Filling = Fermi {
    Temperature [Kelvin] = 300.0
  }

  ####
  KPointsAndWeights = SupercellFolding {
   1   0   0
   0   1   0
   0   0   1
   0.0 0.0 0.0
  }
  ####
}

Options {}
ParserOptions {
  ParserVersion = 4
}

dftb.gen
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

   48  F
  O Zn
    1 1    0.7599150911E+00    0.2993794712E+00    0.6888257079E+00
    2 1    0.7985363100E+00    0.1610358249E+00    0.7345578903E+00
    3 1    0.8914144602E+00    0.6527663076E+00    0.7196132542E+00
    4 1    0.2929570408E+00    0.7510006754E+00    0.7333212782E+00
    5 1    0.3338323664E+00    0.1649990055E+00    0.5960879650E+00
    6 1    0.3301658428E+00    0.6687510163E+00    0.5941141271E+00
    7 1    0.8347890200E+00    0.1656722402E+00    0.5947437957E+00
    8 1    0.8360529036E+00    0.6661644052E+00    0.5961802172E+00
    9 1    0.1666650000E+00    0.3333350000E+00    0.4943832200E+00
   10 1    0.1666650000E+00    0.8333350000E+00    0.4943832200E+00
   11 1    0.6666650000E+00    0.3333350000E+00    0.4943832200E+00
   12 1    0.6666650000E+00    0.8333350000E+00    0.4943832200E+00
   13 1    0.3333350000E+00    0.1666650000E+00    0.3926520800E+00
   14 1    0.3333350000E+00    0.6666650000E+00    0.3926520800E+00
   15 1    0.8333350000E+00    0.1666650000E+00    0.3926520800E+00
   16 1    0.8333350000E+00    0.6666650000E+00    0.3926520800E+00
   17 1    0.1666650000E+00    0.3333350000E+00    0.2909209400E+00
   18 1    0.1666650000E+00    0.8333350000E+00    0.2909209400E+00
   19 1    0.6666650000E+00    0.3333350000E+00    0.2909209400E+00
   20 1    0.6666650000E+00    0.8333350000E+00    0.2909209400E+00
   21 1    0.3333350000E+00    0.6666650000E+00    0.1891898000E+00
   22 1    0.8333350000E+00    0.1666650000E+00    0.1891898000E+00
   23 1    0.3333350000E+00    0.1666650000E+00    0.1891898000E+00
   24 1    0.8333350000E+00    0.6666650000E+00    0.1891898000E+00
   25 2    0.2779755826E+00    0.5722107404E+00    0.6890323365E+00
   26 2    0.5115017005E+00    0.9935237547E+00    0.6925532870E+00
   27 2    0.6824778437E+00    0.7043580735E+00    0.7175240518E+00
   28 2    0.1387176969E+00    0.9707370520E+00    0.7286090496E+00
   29 2    0.1468242856E+00    0.2961873768E+00    0.6158256880E+00
   30 2    0.1606020114E+00    0.8327254074E+00    0.6226498091E+00
   31 2    0.6687273137E+00    0.3368062741E+00    0.6202910950E+00
   32 2    0.6729037083E+00    0.8344594111E+00    0.6229816366E+00
   33 2    0.3333350000E+00    0.1666650000E+00    0.5198892600E+00
   34 2    0.3333350000E+00    0.6666650000E+00    0.5198892600E+00
   35 2    0.8333350000E+00    0.1666650000E+00    0.5198892600E+00
   36 2    0.8333350000E+00    0.6666650000E+00    0.5198892600E+00
   37 2    0.1666650000E+00    0.3333350000E+00    0.4181581100E+00
   38 2    0.1666650000E+00    0.8333350000E+00    0.4181581100E+00
   39 2    0.6666650000E+00    0.3333350000E+00    0.4181581100E+00
   40 2    0.6666650000E+00    0.8333350000E+00    0.4181581100E+00
   41 2    0.3333350000E+00    0.1666650000E+00    0.3164269700E+00
   42 2    0.3333350000E+00    0.6666650000E+00    0.3164269700E+00
   43 2    0.8333350000E+00    0.1666650000E+00    0.3164269700E+00
   44 2    0.8333350000E+00    0.6666650000E+00    0.3164269700E+00
   45 2    0.1666650000E+00    0.8333350000E+00    0.2146958300E+00
   46 2    0.6666650000E+00    0.3333350000E+00    0.2146958300E+00
   47 2    0.1666650000E+00    0.3333350000E+00    0.2146958300E+00
   48 2    0.6666650000E+00    0.8333350000E+00    0.2146958300E+00
    0.0000000000E+00    0.0000000000E+00    0.0000000000E+00
    0.6579600000E+01    0.0000000000E+00    0.0000000000E+00
   -0.3289800000E+01    0.5698100750E+01    0.0000000000E+00
    0.0000000000E+00    0.0000000000E+00    0.2642848600E+02
 		 	   		  
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