# [DFTB-Plus-User] SCC convergence problem

yangming ming_young at msn.com
Thu Jul 23 11:42:29 CEST 2009

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Dear All,

I am a beginner of DFTB+. Currently, I use DFTB+ to calculate ZnO band structure, and got a warning message as following:

********************************************************************************
** Geometry step:    0
********************************************************************************

iSCC Total electronic   Diff electronic      SCC error
1   -0.15653001E+02    0.00000000E+00    0.72663710E-02

Total Energy:                         -15.519984
Total Mermin free energy:             -15.519984
WARNING!
-> SCC is NOT converged, maximal iterations exceeded

________________

Any one there help me to fix this problem? All comments are highly appreciated.

Thanks.

Kevin

_____________________________

The input parameters for calculating this band structure is:

Geometry = GenFormat {
4  S
Zn  O
1 1      0.10584444      1.78119521      0.07906531
2 2      0.10773915      1.78010232      1.89484115
3 1      1.48962855      0.98224506      2.65866079
4 2      1.48773384      0.98333796      4.47443662
0.00000000      0.00000000      0.00000000
2.76344027     -1.59547299      0.00000000
0.00000000      3.19094597      0.00000000
0.00000000      0.00000000      5.15919095
}
Driver = {}
Hamiltonian = DFTB {
SCC = Yes
SCCTolerance = 1.0e-5
MaxSCCIterations = 1
Mixer = Broyden {
MixingParameter = 0.2
CachedIterations = -1
InverseJacobiWeight = 1.000000000000000E-002
MinimalWeight = 1.00000000000000
MaximalWeight = 100000.000000000
WeightFactor = 1.000000000000000E-002
}
KPointsAndWeights = KLines {
1 0.0 0.0 0.5
30 -0.333333 0.66666667 0.5
30 -0.333333 0.66666667 0.0
30 0.0 0.0 0.0
30 0.0 0.5 0.0
}
SlaterKosterFiles = {
Zn-Zn = "Zn-Zn.skf" #(these parameters are from znorg-0-1 set)
Zn-O  = "Zn-O.skf"
O-Zn  = "O-Zn.skf"
O-O   = "O-O.skf"
}
MaxAngularMomentum = {
Zn = "d"
O  = "p"
}
Charge = 0.0
SpinPolarisation = {}
Filling = Fermi {
Temperature = 1.000000000000000E-008
IndependentKFilling = No
}
ElectricField = {}
OrbitalResolvedSCC = No
Eigensolver = DivideAndConquer {}
OldSKInterpolation = No
OrbitalPotential = {}
Dispersion = {}
}
ParserOptions = {
ParserVersion = 3
WriteHSDInput = Yes
WriteXMLInput = No
StopAfterParsing = No
}
Options = {
WriteEigenvectors = Yes
WriteAutotestTag = No
WriteDetailedXML = Yes
WriteResultsTag = Yes
WriteDetailedOut = Yes
WriteBandOut = Yes
AtomResolvedEnergies = Yes
RestartFrequency = 0
RandomSeed = 0
CalculateForces = No
}

The input parameters of static calculations to get the ground state charge density is :

Geometry = GenFormat {
4  S
Zn  O
1 1      0.10584444      1.78119521      0.07906531
2 2      0.10773915      1.78010232      1.89484115
3 1      1.48962855      0.98224506      2.65866079
4 2      1.48773384      0.98333796      4.47443662
0.00000000      0.00000000      0.00000000
2.76344027     -1.59547299      0.00000000
0.00000000      3.19094597      0.00000000
0.00000000      0.00000000      5.15919095
}
Driver =  {}
Hamiltonian = DFTB {
SCC = Yes
SCCTolerance = 1.0e-5
KPointsAndWeights = SupercellFolding {
9 0 0
0  9 0
0  0 6
0.0 0.0 0.5
}
SlaterKosterFiles = {
Zn-Zn = "Zn-Zn.skf"
Zn-O  = "Zn-O.skf"
O-Zn  = "O-Zn.skf"
O-O   = "O-O.skf"
}
MaxAngularMomentum = {
Zn = "d"
O  = "p"
}
Charge = 0.0
}

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