ICODE-ADC/lammps
4
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

clarify use of pair-wise additive pair style requirement as go-between for many-body potentials.

Browse Source
This commit is contained in:
Axel Kohlmeyer
2025-05-28 11:22:39 -04:00
parent ce44faddcf
commit 46b0e48ef3
1 changed files with 10 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
doc/src/pair_hybrid.rst
View File

@ -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 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 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 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** nano-machining work piece). In that case the *mixed* terms
be provided by a pair-wise additive potential (like Lennard-Jones or **should** be provided by a pair-wise additive potential (like
Morse). Outside of this, we *strongly* recommend *against* using Lennard-Jones or Morse) to avoid unexpected behavior and reduce
pair style hybrid with many-body potentials for the following errors. LAMMPS cannot easily check for this condition and thus will
reasons: 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* 1. When trying to combine EAM or MEAM potentials, there is a *large*
error in the embedding term, since it is computed separately for 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 fashion but will need to be applied to multiples of atoms
(e.g. a Tersoff potential of elements A and B includes the (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, 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 3. When one of the sub-styles uses charge-equilibration (= QEq; like
in ReaxFF or COMB) you have inconsistent QEq behavior because in ReaxFF or COMB) you have inconsistent QEq behavior because