git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@242 f3b2605a-c512-4ea7-a41b-209d697bcdaa

doc/pair_style_sw.html

@@ -60,8 +60,8 @@ potentials.
 <P>Stillinger-Weber files in the <I>potentials</I> directory of the LAMMPS
 distribution have a ".sw" suffix.  Lines that are not blank or
 comments (starting with #) define parameters for a triplet of
-elements.  The parameters in a single entry correspond to coefficients
+elements.  The parameters in a single entry correspond to the two-body
-in the formula above:
+and three-body coefficients in the formula above:
 </P>
 <UL><LI>element 1 (the center atom in a 3-body interaction)
 <LI>element 2
@@ -89,8 +89,18 @@ simulation; LAMMPS ignores those entries.
 entries (for SiSiSi, SiSiC, SiCSi, SiCC, CSiSi, CSiC, CCSi, CCC), that
 specify SW parameters for all permutations of the two elements
 interacting in three-body configurations.  Thus for 3 elements, 27
-entries would be required, etc.  Note that due to symmetries, some
+entries would be required, etc.
-parameters will typically be the same in multiple entries.
+</P>
+<P>As annotated above, the first element in the entry is the center atom
+in a three-body interaction.  Thus an entry for SiCC means a Si atom
+with 2 C atoms as neighbors.  By symmetry, three-body parameters for
+SiCSi and SiSiC entries should be the same.  Two-body parameters for
+an interaction come from the entry where the 2nd element is repeated.
+Thus the two-body parameters for Si interacting with C, comes from the
+SiCC entry.  Again by symmetry, the two-body parameters in the SiCC
+and CSiSi entries should thus be the same.  Two-body parameters in
+entries whose 2nd and 3rd element are different (e.g. SiCSi) are
+ignored.
 </P>
 <P><B>Restrictions:</B>
 </P>

doc/pair_style_sw.txt

@@ -57,8 +57,8 @@ potentials.
 Stillinger-Weber files in the {potentials} directory of the LAMMPS
 distribution have a ".sw" suffix.  Lines that are not blank or
 comments (starting with #) define parameters for a triplet of
-elements.  The parameters in a single entry correspond to coefficients
+elements.  The parameters in a single entry correspond to the two-body
-in the formula above:
+and three-body coefficients in the formula above:
 
 element 1 (the center atom in a 3-body interaction)
 element 2
@@ -86,8 +86,18 @@ For a single-element simulation, only a single entry is required
 entries (for SiSiSi, SiSiC, SiCSi, SiCC, CSiSi, CSiC, CCSi, CCC), that
 specify SW parameters for all permutations of the two elements
 interacting in three-body configurations.  Thus for 3 elements, 27
-entries would be required, etc.  Note that due to symmetries, some
+entries would be required, etc.
-parameters will typically be the same in multiple entries.
+
+As annotated above, the first element in the entry is the center atom
+in a three-body interaction.  Thus an entry for SiCC means a Si atom
+with 2 C atoms as neighbors.  By symmetry, three-body parameters for
+SiCSi and SiSiC entries should be the same.  Two-body parameters for
+an interaction come from the entry where the 2nd element is repeated.
+Thus the two-body parameters for Si interacting with C, comes from the
+SiCC entry.  Again by symmetry, the two-body parameters in the SiCC
+and CSiSi entries should thus be the same.  Two-body parameters in
+entries whose 2nd and 3rd element are different (e.g. SiCSi) are
+ignored.
 
 [Restrictions:]
 

doc/pair_style_tersoff.html

@@ -64,8 +64,8 @@ parameters in a single entry correspond to coefficients in the formula
 above:
 </P>
 <UL><LI>element 1 (the center atom in a 3-body interaction)
-<LI>element 2
+<LI>element 2 (the atom bonded to the center atom)
-<LI>element 3
+<LI>element 3 (the atom influencing the 1-2 bond in a bond-order sense)
 <LI>lambda3 (1/distance units)
 <LI>c
 <LI>d
@@ -91,8 +91,19 @@ ignores those entries.
 entries (for SiSiSi, SiSiC, SiCSi, SiCC, CSiSi, CSiC, CCSi, CCC), that
 specify Tersoff parameters for all permutations of the two elements
 interacting in three-body configurations.  Thus for 3 elements, 27
-entries would be required, etc.  Note that due to symmetries, some
+entries would be required, etc.
-parameters will typically be the same in multiple entries.
+</P>
+<P>As annotated above, the first element in the entry is the center atom
+in a three-body interaction and it is bonded to the 2nd atom and the
+bond is influenced by the 3rd atom.  Thus an entry for SiCC means Si
+bonded to a C with another C atom influencing the bond.  Thus
+three-body parameters for SiCSi and SiSiC entries will not, in
+general, be the same.  Two-body parameters for an interaction come
+from the entry where the 2nd element is repeated.  Thus the two-body
+parameters for Si interacting with C, comes from the SiCC entry.  By
+symmetry, the two-body parameters in the SiCC and CSiSi entries should
+thus be the same.  Two-body parameters in entries whose 2nd and 3rd
+element are different (e.g. SiCSi) are ignored.
 </P>
 <P><B>Restrictions:</B>
 </P>

doc/pair_style_tersoff.txt

@@ -61,8 +61,8 @@ parameters in a single entry correspond to coefficients in the formula
 above:
 
 element 1 (the center atom in a 3-body interaction)
-element 2
+element 2 (the atom bonded to the center atom)
-element 3
+element 3 (the atom influencing the 1-2 bond in a bond-order sense)
 lambda3 (1/distance units)
 c
 d
@@ -88,8 +88,19 @@ For a single-element simulation, only a single entry is required
 entries (for SiSiSi, SiSiC, SiCSi, SiCC, CSiSi, CSiC, CCSi, CCC), that
 specify Tersoff parameters for all permutations of the two elements
 interacting in three-body configurations.  Thus for 3 elements, 27
-entries would be required, etc.  Note that due to symmetries, some
+entries would be required, etc.
-parameters will typically be the same in multiple entries.
+
+As annotated above, the first element in the entry is the center atom
+in a three-body interaction and it is bonded to the 2nd atom and the
+bond is influenced by the 3rd atom.  Thus an entry for SiCC means Si
+bonded to a C with another C atom influencing the bond.  Thus
+three-body parameters for SiCSi and SiSiC entries will not, in
+general, be the same.  Two-body parameters for an interaction come
+from the entry where the 2nd element is repeated.  Thus the two-body
+parameters for Si interacting with C, comes from the SiCC entry.  By
+symmetry, the two-body parameters in the SiCC and CSiSi entries should
+thus be the same.  Two-body parameters in entries whose 2nd and 3rd
+element are different (e.g. SiCSi) are ignored.
 
 [Restrictions:]