[lammps-users] Example problem- 2d LJ crack simulation

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1

I have been trying to understand one of LAMMPS’ example problems to simulate crack propagation in a 2d solid. This is to help me understand the input syntax and the output that the software generates. I had a few questions that I was hoping someone could answer.

  1. what part of the script generates a crack? how and why does this happen?
  2. for a 2d lattice specified as hex 0.93, how is the output showing lattice spacing in z? how are the numbers of lattice spacing in x, y, z = 1.11428 1.92998 1.11428 obtained?
  3. how are the total number of atoms in each of the groups calculated and is this of importance for me to know while writing the script?
  4. what does negative energy signify (this may be a very basic question)?
  5. what information does the Temp, E_pair, E_mol, TotEng, Press, and Volume in the output file suggest? Or what should I be looking for?

Thanks,
Mihir.

2

The crack is generated by turning off interactions between atom
types 2,3 with the neigh_modify exclude command. Your other
questions are basic MD or LAMMPS questions. For the latter
you should read the doc pages about the various LAMMPS comands.
For the former, consult a text on MD.

Steve