[lammps-users] Interpreting the output of pair/local combined with property/local

Dear lammps users,

I’m interested in knowing the pair energy for each atom using EAM potential. The documentation tells me that the command compute pair/local and compute property/local can be output into dump local command.

Here’s what I did:

compute 1 all pair/local eng
compute 2 all property/local natom1 natom2

dump 1 all local 10 pair-energy.txt c_1
dump 2 all local 10 pair-index.txt c_2[1] c[2]


I have 640 atoms in my system. There are 10,576 items in pair-energy.txt and 25,952 items in pair-index.


I’m slightly clueless on how to interpret/extract this data. The documentation says that the size of “compute pair/local” is the number of pairs. I supposed that the size of property/local should be twice of the size of “compute pair/local”. However, it’s not quite true. I check the content of “compute property/local” and I found out that in some cases the “A-B” pair is listed twice (as A-B and B-A) while the “B-C” pair is only listed once.

My question is, what can I do to modify these commands so that I can have the following information: “Atom-ID1 Atom-ID2 PairEnergy-of-ID1-2”

Thank you for your kind help.

Tegar Wicaksono

The pair energy between 2 atoms I,J for a many-body
potential like EAM isn't well defined. What do you think
it means?