git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@9535 f3b2605a-c512-4ea7-a41b-209d697bcdaa
This commit is contained in:
@ -51,13 +51,16 @@ off via the <A HREF = "neigh_modify.html">neigh_modify exclude</A> command. The
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<A HREF = "fix_shake.html">fix shake</A> command also effectively turns off certain
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<A HREF = "fix_shake.html">fix shake</A> command also effectively turns off certain
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bond and angle interactions.
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bond and angle interactions.
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</P>
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</P>
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<P>For all styles, an interaction is only turned off (or on) if all the
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<P>For all styles, by default, an interaction is only turned off (or on)
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atoms involved are in the specified group. For style <I>multi</I> this is
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if all the atoms involved are in the specified group. See the <I>any</I>
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the only criterion applied - all types of bonds, angles, dihedrals,
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keyword to change the behavior.
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impropers in the group turned off.
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</P>
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</P>
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<P>For style <I>atom</I>, one or more of the atoms involved must also be of
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<P>For style <I>multi</I> all bond, angle, dihedral, and improper interactions
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the specified type.
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of any type, involving atoms in the group, are turned off.
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</P>
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<P>Style <I>atom</I> is the same as style <I>multi</I> except that in addition, one
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or more of the atoms involved in the bond, angle, dihedral, or
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improper interaction must also be of the specified atom type.
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</P>
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</P>
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<P>For style <I>bond</I>, only bonds are candidates for turn-off, and the bond
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<P>For style <I>bond</I>, only bonds are candidates for turn-off, and the bond
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must also be of the specified type. Styles <I>angle</I>, <I>dihedral</I>, and
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must also be of the specified type. Styles <I>angle</I>, <I>dihedral</I>, and
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@ -84,13 +87,13 @@ force and energy calculations. This means that pairwise computations
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will proceed as if the bond (or angle, etc) were still turned on.
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will proceed as if the bond (or angle, etc) were still turned on.
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</P>
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</P>
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<P>Several keywords can be appended to the argument list to alter the
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<P>Several keywords can be appended to the argument list to alter the
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default behavior.
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default behaviors.
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</P>
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</P>
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<P>The <I>any</I> keyword changes the requirement that all atoms in the bond
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<P>The <I>any</I> keyword changes the requirement that all atoms in the bond
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(angle, etc) must be in the specified group in order to turn-off the
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(angle, etc) must be in the specified group in order to turn-off the
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interaction. If any of the atoms in the interaction are in the
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interaction. Instead, if any of the atoms in the interaction are in
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specified group, it will be turned off (or on if the <I>undo</I> keyword is
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the specified group, it will be turned off (or on if the <I>undo</I>
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used).
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keyword is used).
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</P>
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</P>
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<P>The <I>undo</I> keyword inverts the delete_bonds command so that the
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<P>The <I>undo</I> keyword inverts the delete_bonds command so that the
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specified bonds, angles, etc are turned on if they are currently
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specified bonds, angles, etc are turned on if they are currently
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@ -43,13 +43,16 @@ off via the "neigh_modify exclude"_neigh_modify.html command. The
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"fix shake"_fix_shake.html command also effectively turns off certain
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"fix shake"_fix_shake.html command also effectively turns off certain
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bond and angle interactions.
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bond and angle interactions.
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For all styles, an interaction is only turned off (or on) if all the
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For all styles, by default, an interaction is only turned off (or on)
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atoms involved are in the specified group. For style {multi} this is
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if all the atoms involved are in the specified group. See the {any}
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the only criterion applied - all types of bonds, angles, dihedrals,
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keyword to change the behavior.
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impropers in the group turned off.
|
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For style {atom}, one or more of the atoms involved must also be of
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For style {multi} all bond, angle, dihedral, and improper interactions
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the specified type.
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of any type, involving atoms in the group, are turned off.
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Style {atom} is the same as style {multi} except that in addition, one
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or more of the atoms involved in the bond, angle, dihedral, or
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improper interaction must also be of the specified atom type.
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For style {bond}, only bonds are candidates for turn-off, and the bond
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For style {bond}, only bonds are candidates for turn-off, and the bond
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must also be of the specified type. Styles {angle}, {dihedral}, and
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must also be of the specified type. Styles {angle}, {dihedral}, and
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@ -76,13 +79,13 @@ force and energy calculations. This means that pairwise computations
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will proceed as if the bond (or angle, etc) were still turned on.
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will proceed as if the bond (or angle, etc) were still turned on.
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|
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Several keywords can be appended to the argument list to alter the
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Several keywords can be appended to the argument list to alter the
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default behavior.
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default behaviors.
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|
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The {any} keyword changes the requirement that all atoms in the bond
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The {any} keyword changes the requirement that all atoms in the bond
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(angle, etc) must be in the specified group in order to turn-off the
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(angle, etc) must be in the specified group in order to turn-off the
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interaction. If any of the atoms in the interaction are in the
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interaction. Instead, if any of the atoms in the interaction are in
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specified group, it will be turned off (or on if the {undo} keyword is
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the specified group, it will be turned off (or on if the {undo}
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used).
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keyword is used).
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The {undo} keyword inverts the delete_bonds command so that the
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The {undo} keyword inverts the delete_bonds command so that the
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specified bonds, angles, etc are turned on if they are currently
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specified bonds, angles, etc are turned on if they are currently
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@ -135,13 +135,17 @@ numbers of rigid bodies are simulated.
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number of small rigid bodies. Each body is assigned to the atom
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number of small rigid bodies. Each body is assigned to the atom
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closest to the geometrical center of the body. The fix operates using
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closest to the geometrical center of the body. The fix operates using
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local lists of rigid bodies owned by each processor and information is
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local lists of rigid bodies owned by each processor and information is
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summed and exchanged via local communication between neighboring
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exchanged and summed via local communication between neighboring
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processors when ghost atom info is accumlated. This means that the
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processors when ghost atom info is accumlated.
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ghost atom cutoff be large enough to cover the distance between the
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</P>
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atom that owns the body and every other atom in the body. If the
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<P>IMPORTANT NOTE: To use <I>rigid/small</I> the ghost atom cutoff must be
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<A HREF = "pair_style.html">pair_style</A> cutoff is not of sufficient extent to
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large enough to span the distance between the atom that owns the body
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insure this, then the <A HREF = "communicate.html">communicate cutoff</A> command
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and every other atom in the body. This distance value is printed out
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can be used.
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when the rigid bodies are defined. If the
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<A HREF = "pair_style.html">pair_style</A> cutoff plus neighbor skin does not span
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this distance, then you should use the <A HREF = "communicate.html">communicate
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cutoff</A> command with a setting epsilon larger than
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the distance.
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</P>
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</P>
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<P>Which of the two variants is faster for a particular problem is hard
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<P>Which of the two variants is faster for a particular problem is hard
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to predict. The best way to decide is to perform a short test run.
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to predict. The best way to decide is to perform a short test run.
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@ -121,13 +121,17 @@ The {rigid/small} variant is typically best for a system with a large
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number of small rigid bodies. Each body is assigned to the atom
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number of small rigid bodies. Each body is assigned to the atom
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closest to the geometrical center of the body. The fix operates using
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closest to the geometrical center of the body. The fix operates using
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local lists of rigid bodies owned by each processor and information is
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local lists of rigid bodies owned by each processor and information is
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summed and exchanged via local communication between neighboring
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exchanged and summed via local communication between neighboring
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processors when ghost atom info is accumlated. This means that the
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processors when ghost atom info is accumlated.
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ghost atom cutoff be large enough to cover the distance between the
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atom that owns the body and every other atom in the body. If the
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IMPORTANT NOTE: To use {rigid/small} the ghost atom cutoff must be
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"pair_style"_pair_style.html cutoff is not of sufficient extent to
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large enough to span the distance between the atom that owns the body
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insure this, then the "communicate cutoff"_communicate.html command
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and every other atom in the body. This distance value is printed out
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can be used.
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when the rigid bodies are defined. If the
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"pair_style"_pair_style.html cutoff plus neighbor skin does not span
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this distance, then you should use the "communicate
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cutoff"_communicate.html command with a setting epsilon larger than
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the distance.
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|
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Which of the two variants is faster for a particular problem is hard
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Which of the two variants is faster for a particular problem is hard
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to predict. The best way to decide is to perform a short test run.
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to predict. The best way to decide is to perform a short test run.
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