diff --git a/doc/src/Howto_bpm.rst b/doc/src/Howto_bpm.rst index 8da6511213..2f015162e0 100644 --- a/doc/src/Howto_bpm.rst +++ b/doc/src/Howto_bpm.rst @@ -3,7 +3,6 @@ Bonded particle models The BPM package implements bonded particle models which can be used to simulate mesoscale solids. Solids are constructed as a collection of - particles which each represent a coarse-grained region of space much larger than the atomistic scale. Particles within a solid region are then connected by a network of bonds to provide solid elasticity. @@ -47,33 +46,29 @@ this, LAMMPS requires :doc:`newton ` bond off such that all processors containing an atom know when a bond breaks. Additionally, one must do either (A) or (B). -(A) +A) Use the following special bond settings -Use the following special bond settings + .. code-block:: LAMMPS -.. code-block:: LAMMPS + special_bonds lj 0 1 1 coul 1 1 1 - special_bonds lj 0 1 1 coul 1 1 1 + These settings accomplish two goals. First, they turn off 1-3 and 1-4 + special bond lists, which are not currently supported for BPMs. As + BPMs often have dense bond networks, generating 1-3 and 1-4 special + bond lists is expensive. By setting the lj weight for 1-2 bonds to + zero, this turns off pairwise interactions. Even though there are no + charges in BPM models, setting a nonzero coul weight for 1-2 bonds + ensures all bonded neighbors are still included in the neighbor list + in case bonds break between neighbor list builds. -These settings accomplish two goals. First, they turn off 1-3 and 1-4 -special bond lists, which are not currently supported for BPMs. As -BPMs often have dense bond networks, generating 1-3 and 1-4 special -bond lists is expensive. By setting the lj weight for 1-2 bonds to -zero, this turns off pairwise interactions. Even though there are no -charges in BPM models, setting a nonzero coul weight for 1-2 bonds -ensures all bonded neighbors are still included in the neighbor list -in case bonds break between neighbor list builds. +B) Alternatively, one can simply overlay pair interactions such that all + bonded particles also feel pair interactions. This can be + accomplished by using the *overlay/pair* keyword present in all bpm + bond styles and by using the following special bond settings -(B) + .. code-block:: LAMMPS -Alternatively, one can simply overlay pair interactions such that all -bonded particles also feel pair interactions. This can be accomplished -by using the *overlay/pair* keyword present in all bpm bond styles and -by using the following special bond settings - -.. code-block:: LAMMPS - - special_bonds lj/coul 1 1 1 + special_bonds lj/coul 1 1 1 See the :doc:`Howto ` page on broken bonds for more information.