Author Topic: Unable to run molecular dynamics simulation using semi-empirical calculator  (Read 1063 times)

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Offline dua.harkishan@yahoo.com

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I am trying to run a semi-empirical molecular dynamics calculation on a carbon nanotube. But when I submit the job, I get the error message

  File "CNT.py", line 111, in <module>
    method=method
  File "zipdir/NL/Dynamics/MolecularDynamics/MolecularDynamics.py", line 677, in MolecularDynamics
  File "zipdir/NL/Dynamics/MolecularDynamics/DynamicsEnergyForcesStress.py", line 31, in wrapped_analysis
  File "zipdir/NL/Calculators/DensityFunctionalTheory/LCAOCalculator/Analysis/FastEnergyForcesStress.py", line 45, in forcesFunction
  File "zipdir/NL/Calculators/DensityFunctionalTheory/LCAOCalculator/Analysis/FastEnergyForcesStress.py", line 71, in _checkAndUpdate
  File "zipdir/NL/Calculators/DensityFunctionalTheory/LCAOCalculator/Analysis/FastEnergyForcesStress.py", line 108, in _update
  File "zipdir/NL/Calculators/SemiEmpirical/HuckelCalculator/Analysis/EnergyForcesStress.py", line 34, in calculateHuckelEnergyForcesStress
  File "zipdir/NL/Calculators/SemiEmpirical/HuckelCalculator/Analysis/EnergyForcesStressUtilities.py", line 216, in setupEnergyForcesStress
NL.ComputerScienceUtilities.Exceptions.NLValueError: No PairPotential given, which is required in order to calculate forces or stress.

Attached with this message is the input file that I am trying to run.

Offline Anders Blom

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Yes, this is expected for most semiempirical models, as they only contain parameters for the electronic structure, not forces and stress, and hence cannot be used for geometry optimization, MD, or phonons. The exception is DFTB, which typically works for all that.