half of periodic box warning

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1

Hello All,

I have a simulation box with lengths 680A x 20A x 680A and PBC in the 3 axis. I’m getting the warning:

Bond/angle/dihedral extent > half of periodic box length

My pair cutoff is 15.0A and my longest length bewteen 1-4 atoms (dihedral) is ~10A.

Is this warning something to be worried about and if so, is there a proper way to handle a “thin film” in LAMMPS?

Thanks

2

John,
If you are simulating ‘thin film’, then I don’t know how good is the assumption of making the 2 nm dimension periodic. You could introduce some empty space I’m that dimension to get more realistic model.

Just a thought.

3

Hello All,

I have a simulation box with lengths 680A x 20A x 680A and PBC in the 3
axis. I'm getting the warning:

    Bond/angle/dihedral extent > half of periodic box length

My pair cutoff is 15.0A and my longest length bewteen 1-4 atoms (dihedral)
is ~10A.

Is this warning something to be worried about and if so, is there a proper
way to handle a "thin film" in LAMMPS?

unless you have bonds that have to cross periodic boundaries to build
an infinite chain or plane, yes, you need to be worried and need to
examine your data file. you may have incorrectly assigned image flags.

this is a general issue and not specific to thin films. as vikas
mentioned, it seems odd that you need periodicity in all 3 directions.

axel.