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Modified discussion of twobody symmetry 

git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@3958 f3b2605a-c512-4ea7-a41b-209d697bcdaa
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athomps 2010-04-06 15:10:15 +00:00
parent b12d4c13d1
commit 169ffd2711
2 changed files with 18 additions and 6 deletions
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12
doc/pair_tersoff.html
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@ -107,13 +107,19 @@ three-body parameters for SiCSi and SiSiC entries will not, in
general, be the same. The parameters used for the two-body
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 twobody parameters in the SiCC and CSiSi
entries should thus be the same. The parameters used for a particular
SiCC entry.
</P>
<P>The parameters used for a particular
three-body interaction come from the entry with the corresponding
three elements. The parameters used only for two-body interactions
(n, beta, lambda2, B, lambda1, and A) in entries whose 2nd and 3rd
element are different (e.g. SiCSi) are not used for anything and can
be set to 0.0 if desired.
be set to 0.0 if desired.
</P>
<P>Note that the twobody parameters in entries such as SiCC and CSiSi
are often the same, due to the common use of symmetric mixing rules,
but this is not always the case. For example, the beta and n parameters in
Tersoff_2 <A HREF = "#Tersoff_2">(Tersoff_2)</A> are not symmetric.
</P>
<P>We chose the above form so as to enable users to define all commonly
used variants of the Tersoff potential. In particular, our form

12
doc/pair_tersoff.txt
View File

@ -104,13 +104,19 @@ three-body parameters for SiCSi and SiSiC entries will not, in
general, be the same. The parameters used for the two-body
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 twobody parameters in the SiCC and CSiSi
entries should thus be the same. The parameters used for a particular
SiCC entry.
The parameters used for a particular
three-body interaction come from the entry with the corresponding
three elements. The parameters used only for two-body interactions
(n, beta, lambda2, B, lambda1, and A) in entries whose 2nd and 3rd
element are different (e.g. SiCSi) are not used for anything and can
be set to 0.0 if desired.
be set to 0.0 if desired.
Note that the twobody parameters in entries such as SiCC and CSiSi
are often the same, due to the common use of symmetric mixing rules,
but this is not always the case. For example, the beta and n parameters in
Tersoff_2 "(Tersoff_2)"_#Tersoff_2 are not symmetric.
We chose the above form so as to enable users to define all commonly
used variants of the Tersoff potential. In particular, our form