Using OPLS on Nitrocellulose with LAMMPS

Using lammps-3Mar20

I think my issue is with the way I am using the forcefield, but I hope this is the right place to ask this.

I am trying to run simulations on nitrocellulose. The calculations are running fine, mostly because I am mostly still using the examples from the moltemplate website.

However the ONO2 functional groups are not behaving as one would expect – the bond angles are closing up.

I think this is due to the descriptions I am choosing for the atoms, although I’ve been trying to correct this. I have been told that I can specify the angle_coeff, but I am not sure how to do this.

If anyone could help I would be very grateful

Thank you

Catriona Gibbon

bond_angle.png

dimer_nc.lt (8.05 KB)

oplsaa.lt (561 KB)

run.in.min (888 Bytes)

system.lt (521 Bytes)

Using lammps-3Mar20

I think my issue is with the way I am using the forcefield, but I hope this is the right place to ask this.

I am trying to run simulations on nitrocellulose. The calculations are running fine, mostly because I am mostly still using the examples from the moltemplate website.

However the ONO2 functional groups are not behaving as one would expect – the bond angles are closing up.

I think this is due to the descriptions I am choosing for the atoms, although I’ve been trying to correct this. I have been told that I can specify the angle_coeff, but I am not sure how to do this.

If anyone could help I would be very grateful

Thank you

Catriona Gibbon

(Sorry if this is a resubmission, but I haven’t heard anything back yet)

bond_angle.png

dimer_nc.lt (8.05 KB)

oplsaa.lt (561 KB)

run.in.min (888 Bytes)

system.lt (521 Bytes)

When you are not getting a reaction after a few days that usually means one of three things:

  • people think this is a problem specific to a particular feature or LAMMPS-related software and want to let the author of that code respond
  • people don’t know what to answer/recommend or are confused by what you are asking
  • people think that this is something that you should know or figure out by yourself or discuss with your adviser/supervisor/colleagues that have more insight into the specifics of your research

In those cases it is rarely productive to repost the exact same text and files.

Axel.