diff -Naur lammps-14Feb08/doc/atom_modify.html lammps-15Feb08/doc/atom_modify.html --- lammps-14Feb08/doc/atom_modify.html 2006-09-21 10:22:34.000000000 -0600 +++ lammps-15Feb08/doc/atom_modify.html 2008-02-15 12:09:18.000000000 -0700 @@ -17,15 +17,17 @@
map value = array or hash +map value = array or hash + first value = group-ID = group whose atoms will appear first in internal atom lists
Examples:
-atom_modify map hash +atom_modify map hash +atom_modify first colloidDescription:
@@ -43,6 +45,26 @@ proportional to N/P on each processor, where P is the total number of processors running the simulation. +The first keyword allows a group to be specified whose +atoms will be maintained as the first atoms in each processor's list +of owned atoms. This in only useful when the specified group is a +small fraction of all the atoms, and there are other operations LAMMPS +is performing that will be sped-up significantly by being able to loop +over the smaller set of atoms. Otherwise the reordering required by +this option will be a net slow-down. The neigh_modify +include and communicate group +commands are two examples of commands that require this setting to +work efficiently. Several fixes, most notably time +integration fixes like fix nve, also take advantage of +this setting if the group they operate on is the group specified by +this command. +
+Note that because the atom_modify command must be used in an input +script before a simulation is setup and groups are defined, this means +the first keyword will specify a group that is not yet defined. +This is OK; LAMMPS will check that the group exists before the first +simulation is performed. +
Restrictions:
This command must be used before the simulation box is defined by a @@ -52,7 +74,8 @@
Default:
-By default, atomic (non-molecular) problems do not allocate maps. -For molecular problems, the option default is map = array. +
By default, atomic (non-molecular) problems do not allocate maps. For +molecular problems, the option default is map = array. By default, +first = all.