From 169ffd2711cb296a79067f8b68376e0550945249 Mon Sep 17 00:00:00 2001 From: athomps Date: Tue, 6 Apr 2010 15:10:15 +0000 Subject: [PATCH] Modified discussion of twobody symmetry git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@3958 f3b2605a-c512-4ea7-a41b-209d697bcdaa --- doc/pair_tersoff.html | 12 +++++++++--- doc/pair_tersoff.txt | 12 +++++++++--- 2 files changed, 18 insertions(+), 6 deletions(-) diff --git a/doc/pair_tersoff.html b/doc/pair_tersoff.html index 4ac172f5db..e38c67bd95 100644 --- a/doc/pair_tersoff.html +++ b/doc/pair_tersoff.html @@ -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. +

+

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) 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 diff --git a/doc/pair_tersoff.txt b/doc/pair_tersoff.txt index e78a516086..6024af80c4 100644 --- a/doc/pair_tersoff.txt +++ b/doc/pair_tersoff.txt @@ -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