[DFTB-Plus-User] Failure on MD run

[Ben Hourahine]

Your initial geometry is probably the cause of the problem, did you 
relax it first with conjugate
gradient or similar? Also the thermostat coupling strength is very large 
(temperature
will be very strongly forced towards 300K).

On 20/04/11 04:55, bigcontinent wrote:
> 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


-- 
      Dr. B. Hourahine, SUPA, Department of Physics,
    University of Strathclyde, John Anderson Building,
           107 Rottenrow, Glasgow G4 0NG, UK.
     +44 141 548 2325, benjamin.hourahine at strath.ac.uk
    The University of Strathclyde is a charitable body,
registered in Scotland, with registration number SC015263

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