diff --git a/doc/src/pair_hybrid.rst b/doc/src/pair_hybrid.rst index 4f996d60ff..05cc8ddf24 100644 --- a/doc/src/pair_hybrid.rst +++ b/doc/src/pair_hybrid.rst @@ -109,11 +109,14 @@ have the same molecule ID), the second to inter-molecular interactions of how this is set up, there will be *errors*. The major use case where the error is *small*, is when the many-body sub-styles are used on different objects (for example a slab and a liquid, a metal and a - nano-machining work piece). In that case the *mixed* terms **must** - be provided by a pair-wise additive potential (like Lennard-Jones or - Morse). Outside of this, we *strongly* recommend *against* using - pair style hybrid with many-body potentials for the following - reasons: + nano-machining work piece). In that case the *mixed* terms + **should** be provided by a pair-wise additive potential (like + Lennard-Jones or Morse) to avoid unexpected behavior and reduce + errors. LAMMPS cannot easily check for this condition and thus will + accept good and bad choices alike. + + Outside of this, we *strongly* recommend *against* using pair style + hybrid with many-body potentials for the following reasons: 1. When trying to combine EAM or MEAM potentials, there is a *large* error in the embedding term, since it is computed separately for @@ -125,7 +128,8 @@ have the same molecule ID), the second to inter-molecular interactions fashion but will need to be applied to multiples of atoms (e.g. a Tersoff potential of elements A and B includes the interactions A-A, B-B, A-B, A-A-A, A-A-B, A-B-B, A-B-A, B-A-A, - B-A-B, B-B-A, B-B-B; AIREBO also considers quadruples). + B-A-B, B-B-A, B-B-B; AIREBO also considers all quadruples of + atom elements). 3. When one of the sub-styles uses charge-equilibration (= QEq; like in ReaxFF or COMB) you have inconsistent QEq behavior because