[lammps-users] compute heat/flux for atom groups

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1

In the documentation for the command: “

The compute takes three arguments which are IDs of other computes. One calculates per-atom kinetic energy (ke-ID), one calculates per-atom potential energy (pe-ID), and the third calcualtes per-atom stress (stress-ID). These should be defined for the same group used by compute heat/flux, though LAMMPS does not check for this. “

But if specify a compute heat/flux for more than one group, each group having its own ke/atom, pe/atom, stress/atom calculation I get the warning: more than one compute ke/atom.

Is it safe to ignore this message? Or should I compute all ke/atom, pe/atom, stress/atom and then specify my atom groups in multiple heat/flux commands; which seems to go against the quoted documentation?

2

it's just a warning, with respect to code speed.
e.g.each per-atom compute loops over all atoms,
so that might be slightly inefficient.

You can either use two compute ke/atom, or you
could use one for group all, and refer to it
in 2 compute heat/flux commands.

What you don't want to do is the opposite. Have
a compute heat/flux on group all, but reference
a compute ke/atom that operates on a subset
of atoms, since then the KE for the other atoms
will be 0.0

Steve