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Modified description of two-body and three-body parameter treatment

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git-svn-id: svn://svn.icms.temple.edu/lammps-ro/trunk@363 f3b2605a-c512-4ea7-a41b-209d697bcdaa
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athomps
2007-03-06 17:09:05 +00:00
parent ed114fb152
commit 58e5b3cf0f
2 changed files with 28 additions and 17 deletions
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26
doc/pair_sw.txt
View File

@ -74,9 +74,11 @@ B
p
q :ul
The epsilon, sigma, a, A, B, p, and q parameters are for two-body
interactions. The lambda, gamma, and costheta0 parameters are for
three-body interactions. The non-annotated parameters are unitless.
The A, B, p, and q parameters are used only for two-body
interactions. The lambda, gamma, and costheta0 parameters are used only for
three-body interactions. The epsilon, sigma and a parameters are used
for both two-body and three-body interactions.
The non-annotated parameters are unitless.
The Stillinger-Weber potential file must contain entries for all the
elements listed in the pair_coeff command. It can also contain
@ -93,13 +95,17 @@ entries would be required, etc.
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.
SiCSi and SiSiC entries should 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.
Again by symmetry, the two-body parameters in the SiCC
and CSiSi entries should thus be the same.
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 (A, B, p, and q)
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.
[Restrictions:]

19
doc/pair_tersoff.txt
View File

@ -76,10 +76,11 @@ D (distance units)
lambda1 (1/distance units)
A (energy units) :ul
The n, beta, lambda2, B, R, D, lambda1, and A parameters are for
The n, beta, lambda2, B, lambda1, and A parameters are only used for
two-body interactions. The lambda3, c, d, and costheta0 parameters
are for three-body interactions. The non-annotated parameters are
unitless.
are only used for three-body interactions. The R and D parameters
are used for both two-body and three-body interactions. The
non-annotated parameters are unitless.
The Tersoff potential file must contain entries for all the elements
listed in the pair_coeff command. It can also contain entries for
@ -98,12 +99,16 @@ 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
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 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.
symmetry, the twobody parameters in the SiCC and CSiSi entries should
thus be the same. 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.
[Restrictions:]