[lammps-users] asking a abou tersoff parameters in lammps

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1

Dear Steve and Aidan,
In lammps man-doc on pair_style tersoff command said:

¨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.¨

But in actuall file (in your directoty potential/) they are not the same as (SiC.tersoff as well as SiCGe.tersoff) I extract here as:

m, gamma, lambda3, c, d, costheta0, n, beta, lambda2, B, R, D, lambda1, A

Si C C 3.0 1.0 0.0 100390 16.217 - .59825 .787340 0.0000011 1.97205 395.126 2.36 0.15 2.9839 1597.3111
C Si Si 3.0 1.0 0.0 38049 4.3484 - .57058 .727510 .00000015724 1.97205 395.126 2.36 0.15 2.9839 1597.3111

Pls check again or where am I wrong. And general how can I construct A-B-C pair with B not equal C?
Thnks
VNT

2

I'll let Aidan answer - I think the answer is that some of the params appear in
more than one place (b/c of symmetry), so only one of them is used. Thus
to avoid confusion, they should be listed the same, but they don't have to be.

Steve