How to unify tag[i] and ilist[i] when only using single processor?

LAMMPS LAMMPS Development
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1

Hi,
I am writing a new pari style and I need to unify these two to test my code.

Can I unify them by only reordering the lammps data file? Or add some configs in lammps input file?

Thank you.

2

Never. Atoms in the neighbor list are reordered at each neighbor list creation.

But, you can always identify which local index a specific atom with a given atom ID has, i.e. which “i” you need to used to get a specific atom->tag[i]. This is done with atom->map().

This is used in several of the test programs in the “unittest” tree. E.g. in the test program for atom styles unittest/formats/test_atom_styles.cpp. Check out the GETIDX macro!

3

So it’s a hash map. Thank you!

4

Not necessarily. See atom_modify command — LAMMPS documentation