[DFTB-Plus-User] Scalapack error in MD run

[Luca Babetto]

Dear all,

I'm running a MD simulation on a urea molecule explicitly solvated with 200 water molecules. For this simulation I am using the modified 3OBw parameters for water developed in the paper J. Phys. Chem. B 2014, 118, 38, 11007–11027. In particular, these modified parameters contain Slater-Koster files for O-O, H-H, and O-H pairs. All other parameters are taken from the standard 3OB set.

I am regularly encountering a hard crash due to Scalapack when carrying out the simulation on the solvated urea after a few hundred steps. I'm using the latest mpi-parallel DFTB+ version on a Ubuntu 20.04 machine. The analogous simulation in which only water is present (box with 200 molecules which only uses the 3OBw parameters) is running normally.

I don't see any red flag in this simulation, the temperature is oscillating around the correct value and the energies do not seem to be diverging. Looking at the geo_end.xyz file directly, atoms do not seem to be behaving in a weird way.

I suspect, reading back at other topics in the mailing list, that this could be due to a mismatch in the SK files, even though these modified 3OBw parameters should not differ significantly from the standard 3OB parameters, and indeed the simulation is able to run for a few hundred steps before crashing.

Does anyone have any idea on why this issue is occurring? Let me know if I should try something else to diagnose the problem!

Please find below the .zip with all the input/output files:

files: https://we.tl/t-3IpuqXehoL

For completeness, here is the dftb_in.hsd file you can also find in the archive above:

Geometry = GenFormat {
  <<< "urea_solvated.gen"
}

Driver = VelocityVerlet{
  TimeStep [fs] = 1.0
  Thermostat = NoseHoover {
    Temperature [Kelvin] = 298
    CouplingStrength [cm^-1] = 3200
  }
  Steps = 4000000
  MovedAtoms = 1:-1
  MDRestartFrequency = 1
}

Hamiltonian = DFTB {
  Scc = Yes
  SlaterKosterFiles = Type2FileNames {
    Prefix = "3ob/3obw/"
    Separator = "-"
    Suffix = ".skf"
  }
  ThirdOrderFull = Yes
  HubbardDerivs {
    C = -0.1492
    O = -0.1575
    H = -0.1857
    N = -0.1535
  }
  HCorrection = Damping {
    Exponent = 4.00
  }
  MaxAngularMomentum {
    C = "p"
    O = "p"
    N = "p"
    H = "s"
  }
  kPointsAndWeights = { 0.0 0.0 0.0 1.0 }
}

Options {}

ParserOptions {
  ParserVersion = 11
}

As always, thanks to all the developers for their amazing work on this piece of software! :)

Kind regards

Luca
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