Simulation stops after 1.8 million steps

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1

Hello Everyone,

I have recently started using LAMMPS. My system consists two single wall carbon nanotubes in aqueous dispersion.
I am carrying out Umbrella Sampling simulations (using fix spring) at varying separations between the two tubes like 8, 9, 10,…,18 angstrom.
I am using CHARMM force field. Simulation time is 10 ns and there are 10,000,000 time steps.

My problem is, in case of 16 angstrom separation, the simulation stops after 1850000 steps. It shows the following error.

‘‘ERROR on proc 6: Angle atoms 3486 3485 3487 missing on proc 6 at step 1850100’’

All simulations are run in a parallel mode on 8 processors. This problem occurs only in case of 16 angstrom separation. For higher and lower values it is running properly.

I would really appreciate if any one can help me on this sort of error.I tried to mention as much information as possible.
If I missed any important information I apologize for that, and if need any further clarification on the above problem, I can provide additional information as well.

Thank you in advance, for your time and consideration in answering my query.

regards,
Nabaneeta

2

Hello Everyone,

I have recently started using LAMMPS. My system consists two single wall
carbon nanotubes in aqueous dispersion.
I am carrying out Umbrella Sampling simulations (using fix spring) at
varying separations between the two tubes like 8, 9, 10,....,18 angstrom.
I am using CHARMM force field. Simulation time is 10 ns and there are
10,000,000 time steps.

My problem is, in case of 16 angstrom separation, the simulation stops after
1850000 steps. It shows the following error.

''ERROR on proc 6: Angle atoms 3486 3485 3487 missing on proc 6 at step
1850100''

All simulations are run in a parallel mode on 8 processors. This problem
occurs only in case of 16 angstrom separation. For higher and lower values
it is running properly.

as far as i can tell, this would only be by chance.
the error message that you are getting hints that
you may be using too aggressive neighbor list
update settings. please check your log files.
do you get any "dangerous builds" in the final
neighbor list statistics?

axel.

3

And look at doc/Section_errors.html which explains
all error messages.

Steve