[DFTB-Plus-User] Failure on MD run

[bigcontinent]

Hi, everyone
     I would like to run an MD simulation of C60 using DFTB+, but I get the following message, 

********************************************************************************
** Geometry step: 3
********************************************************************************

  iSCC Total electronic   Diff electronic      SCC error    
ERROR!
-> Failure in diagonalisation routine dsygvd, non-positive definite overlap! Minor      1 responsible.

       My investigated sytem is C60 and temperature is set to 300K, using Berendsen  ensemble . 

My INPUT

Driver = VelocityVerlet{
  Steps = 2500000                  # Number of MD steps to perform
  TimeStep [Femtosecond] = 0.2      # Time step in femtoseconds
  OutputPrefix = "last"
  Thermostat =  Berendsen {  
  Temperature [Kelvin] = 300.0
 CouplingStrength = 500.0
}
}

Hamiltonian = DFTB {
  SCC = Yes
  SCCTolerance = 1.0e-5
  MaxSCCIterations = 1000
  Mixer = Broyden {
    MixingParameter = 0.2
  }

  SlaterKosterFiles = {
    C-C = "C-C.skf"
  }

MaxAngularMomentum = {
    C = "p"
  }
  Charge = 0.0
  SpinPolarisation = {}
  Filling = Fermi {
    Temperature [Kelvin] = 300.0
  }
}

Options = {}

ParserOptions = {
  ParserVersion = 3
}


        Please give me some advices. 
        Thank you very much





2011-04-20 



bigcontinent 
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