Getting the kinetic energy of molecules

LAMMPS LAMMPS General Discussion
1

Hi all,

I am running some high energy impact simulations on a mineral. I am using ReaxFF so I am seeing some molecules being ejected from the surface.

Is there a way to get the kinetic energy of the molecules? Due to bond breaking and formation of ReaxFF the molecules that are ejected don’t have the same mol_ID.

Many thanks,

Anastasis

2

You could re-assign the molecule IDs based on the per-atom property computed by fix reaxff/species.

You could also identify ejected atoms using a region.

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3

Thanks for the reply! I implimented these methods and can get the KE of each individual ejected atom, but not sure on how to obtain the KE of the molecule.

4

You could define a compute chunk/atom based on the fix reaxff/species per-atom data, then define a compute ke/atom and finally use compute reduce/chunk on the ke/atom data to sum the per-atom energies into per-chunk energies, which would correspond to the per-molecule kinetic energy.

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