git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9535 f3b2605a-c512-4ea7-a41b-209d697bcdaa

This commit is contained in:
sjplimp
2013-02-19 16:25:08 +00:00
parent 28cd1e1af6
commit a18d1163c2
4 changed files with 48 additions and 34 deletions

View File

@ -51,13 +51,16 @@ off via the <A HREF = "neigh_modify.html">neigh_modify exclude</A> command. The
<A HREF = "fix_shake.html">fix shake</A> command also effectively turns off certain <A HREF = "fix_shake.html">fix shake</A> command also effectively turns off certain
bond and angle interactions. bond and angle interactions.
</P> </P>
<P>For all styles, an interaction is only turned off (or on) if all the <P>For all styles, by default, an interaction is only turned off (or on)
atoms involved are in the specified group. For style <I>multi</I> this is if all the atoms involved are in the specified group. See the <I>any</I>
the only criterion applied - all types of bonds, angles, dihedrals, keyword to change the behavior.
impropers in the group turned off.
</P> </P>
<P>For style <I>atom</I>, one or more of the atoms involved must also be of <P>For style <I>multi</I> all bond, angle, dihedral, and improper interactions
the specified type. of any type, involving atoms in the group, are turned off.
</P>
<P>Style <I>atom</I> is the same as style <I>multi</I> except that in addition, one
or more of the atoms involved in the bond, angle, dihedral, or
improper interaction must also be of the specified atom type.
</P> </P>
<P>For style <I>bond</I>, only bonds are candidates for turn-off, and the bond <P>For style <I>bond</I>, only bonds are candidates for turn-off, and the bond
must also be of the specified type. Styles <I>angle</I>, <I>dihedral</I>, and must also be of the specified type. Styles <I>angle</I>, <I>dihedral</I>, and
@ -84,13 +87,13 @@ force and energy calculations. This means that pairwise computations
will proceed as if the bond (or angle, etc) were still turned on. will proceed as if the bond (or angle, etc) were still turned on.
</P> </P>
<P>Several keywords can be appended to the argument list to alter the <P>Several keywords can be appended to the argument list to alter the
default behavior. default behaviors.
</P> </P>
<P>The <I>any</I> keyword changes the requirement that all atoms in the bond <P>The <I>any</I> keyword changes the requirement that all atoms in the bond
(angle, etc) must be in the specified group in order to turn-off the (angle, etc) must be in the specified group in order to turn-off the
interaction. If any of the atoms in the interaction are in the interaction. Instead, if any of the atoms in the interaction are in
specified group, it will be turned off (or on if the <I>undo</I> keyword is the specified group, it will be turned off (or on if the <I>undo</I>
used). keyword is used).
</P> </P>
<P>The <I>undo</I> keyword inverts the delete_bonds command so that the <P>The <I>undo</I> keyword inverts the delete_bonds command so that the
specified bonds, angles, etc are turned on if they are currently specified bonds, angles, etc are turned on if they are currently

View File

@ -43,13 +43,16 @@ off via the "neigh_modify exclude"_neigh_modify.html command. The
"fix shake"_fix_shake.html command also effectively turns off certain "fix shake"_fix_shake.html command also effectively turns off certain
bond and angle interactions. bond and angle interactions.
For all styles, an interaction is only turned off (or on) if all the For all styles, by default, an interaction is only turned off (or on)
atoms involved are in the specified group. For style {multi} this is if all the atoms involved are in the specified group. See the {any}
the only criterion applied - all types of bonds, angles, dihedrals, keyword to change the behavior.
impropers in the group turned off.
For style {atom}, one or more of the atoms involved must also be of For style {multi} all bond, angle, dihedral, and improper interactions
the specified type. of any type, involving atoms in the group, are turned off.
Style {atom} is the same as style {multi} except that in addition, one
or more of the atoms involved in the bond, angle, dihedral, or
improper interaction must also be of the specified atom type.
For style {bond}, only bonds are candidates for turn-off, and the bond For style {bond}, only bonds are candidates for turn-off, and the bond
must also be of the specified type. Styles {angle}, {dihedral}, and must also be of the specified type. Styles {angle}, {dihedral}, and
@ -76,13 +79,13 @@ force and energy calculations. This means that pairwise computations
will proceed as if the bond (or angle, etc) were still turned on. will proceed as if the bond (or angle, etc) were still turned on.
Several keywords can be appended to the argument list to alter the Several keywords can be appended to the argument list to alter the
default behavior. default behaviors.
The {any} keyword changes the requirement that all atoms in the bond The {any} keyword changes the requirement that all atoms in the bond
(angle, etc) must be in the specified group in order to turn-off the (angle, etc) must be in the specified group in order to turn-off the
interaction. If any of the atoms in the interaction are in the interaction. Instead, if any of the atoms in the interaction are in
specified group, it will be turned off (or on if the {undo} keyword is the specified group, it will be turned off (or on if the {undo}
used). keyword is used).
The {undo} keyword inverts the delete_bonds command so that the The {undo} keyword inverts the delete_bonds command so that the
specified bonds, angles, etc are turned on if they are currently specified bonds, angles, etc are turned on if they are currently

View File

@ -135,13 +135,17 @@ numbers of rigid bodies are simulated.
number of small rigid bodies. Each body is assigned to the atom number of small rigid bodies. Each body is assigned to the atom
closest to the geometrical center of the body. The fix operates using closest to the geometrical center of the body. The fix operates using
local lists of rigid bodies owned by each processor and information is local lists of rigid bodies owned by each processor and information is
summed and exchanged via local communication between neighboring exchanged and summed via local communication between neighboring
processors when ghost atom info is accumlated. This means that the processors when ghost atom info is accumlated.
ghost atom cutoff be large enough to cover the distance between the </P>
atom that owns the body and every other atom in the body. If the <P>IMPORTANT NOTE: To use <I>rigid/small</I> the ghost atom cutoff must be
<A HREF = "pair_style.html">pair_style</A> cutoff is not of sufficient extent to large enough to span the distance between the atom that owns the body
insure this, then the <A HREF = "communicate.html">communicate cutoff</A> command and every other atom in the body. This distance value is printed out
can be used. when the rigid bodies are defined. If the
<A HREF = "pair_style.html">pair_style</A> cutoff plus neighbor skin does not span
this distance, then you should use the <A HREF = "communicate.html">communicate
cutoff</A> command with a setting epsilon larger than
the distance.
</P> </P>
<P>Which of the two variants is faster for a particular problem is hard <P>Which of the two variants is faster for a particular problem is hard
to predict. The best way to decide is to perform a short test run. to predict. The best way to decide is to perform a short test run.

View File

@ -121,13 +121,17 @@ The {rigid/small} variant is typically best for a system with a large
number of small rigid bodies. Each body is assigned to the atom number of small rigid bodies. Each body is assigned to the atom
closest to the geometrical center of the body. The fix operates using closest to the geometrical center of the body. The fix operates using
local lists of rigid bodies owned by each processor and information is local lists of rigid bodies owned by each processor and information is
summed and exchanged via local communication between neighboring exchanged and summed via local communication between neighboring
processors when ghost atom info is accumlated. This means that the processors when ghost atom info is accumlated.
ghost atom cutoff be large enough to cover the distance between the
atom that owns the body and every other atom in the body. If the IMPORTANT NOTE: To use {rigid/small} the ghost atom cutoff must be
"pair_style"_pair_style.html cutoff is not of sufficient extent to large enough to span the distance between the atom that owns the body
insure this, then the "communicate cutoff"_communicate.html command and every other atom in the body. This distance value is printed out
can be used. when the rigid bodies are defined. If the
"pair_style"_pair_style.html cutoff plus neighbor skin does not span
this distance, then you should use the "communicate
cutoff"_communicate.html command with a setting epsilon larger than
the distance.
Which of the two variants is faster for a particular problem is hard Which of the two variants is faster for a particular problem is hard
to predict. The best way to decide is to perform a short test run. to predict. The best way to decide is to perform a short test run.