diff --git a/doc/src/Errors_details.rst b/doc/src/Errors_details.rst index eba240aef7..4b510f4902 100644 --- a/doc/src/Errors_details.rst +++ b/doc/src/Errors_details.rst @@ -159,13 +159,17 @@ angle, dihedral, or improper with just one atom in the actual sub-domain. Typically, this cutoff is set to the largest cutoff from the :doc:`pair style(s) ` plus the :doc:`neighbor list skin distance ` and will typically be sufficient for all bonded -interactions. But if the pair style cutoff is small, this may not be -enough. LAMMPS will print a warning in this case using some heuristic -based on the equilibrium bond length, but that still may not be -sufficient for cases where the force constants are small and thus bonds -may be stretched very far. The communication cutoff can be adjusted -with :doc:`comm_modify cutoff \ `, but setting this -too large will waste CPU time and memory. +interactions. But if the pair style cutoff is small (e.g. with a +repulsive-only Lennard-Jones potential) this may not be enough. It is +even worse if there is no pair style defined (or the pair style is set +to "none"), since then there will be no ghost atoms created at all. + +The communication cutoff can be set or adjusted with :doc:`comm_modify +cutoff \ `, but setting this too large will waste +CPU time and memory. LAMMPS will print warnings in these cases. For +bonds it uses some heuristic based on the equilibrium bond length, but +that still may not be sufficient for cases where the force constants are +small and thus bonds may be stretched very far. .. _hint09: diff --git a/src/comm_brick.cpp b/src/comm_brick.cpp index 1e9bfe6aca..4720694759 100644 --- a/src/comm_brick.cpp +++ b/src/comm_brick.cpp @@ -209,8 +209,8 @@ void CommBrick::setup() double cut = get_comm_cutoff(); if ((cut == 0.0) && (me == 0)) - error->warning(FLERR,"Communication cutoff is 0.0. No ghost atoms " - "will be generated. Atoms may get lost."); + error->warning(FLERR,"Communication cutoff is 0.0. No ghost atoms will be generated. " + "Energies and forces may be wrong and atoms may get lost."); if (mode == Comm::MULTI) { double **cutcollectionsq = neighbor->cutcollectionsq; diff --git a/src/comm_tiled.cpp b/src/comm_tiled.cpp index bc4674a6b6..6a20728790 100644 --- a/src/comm_tiled.cpp +++ b/src/comm_tiled.cpp @@ -280,8 +280,8 @@ void CommTiled::setup() double cut = get_comm_cutoff(); if ((cut == 0.0) && (me == 0)) - error->warning(FLERR,"Communication cutoff is 0.0. No ghost atoms " - "will be generated. Atoms may get lost."); + error->warning(FLERR,"Communication cutoff is 0.0. No ghost atoms will be generated. " + "Energies and forces may be wrong and atoms may get lost."); if (triclinic == 0) cutghost[0] = cutghost[1] = cutghost[2] = cut; else {