Dear All:
I'm trying to run simulations for molecules containing structures such as
C6H5-C-triple-bond-C-C6H5
using GAFF force field.
So I checked gaff force field for sp carbon parameters. However, I
found that all of the dihedral parameters for sp carbon such as cg
(Inner Sp carbons in conjugated systems) have zero PK value. For
example:
X -cg-cg-X 1 0.000 180.000 2.000 for both
triple and single bonds
For the sp2-sp conjugate system, I don't think the zero PK is correct.
Are there any particular reasons to have this zero here or the zero is
just a placeholder and the parameter is still unknown?
Another question is: The definition of "ch" type is:" identical to
cg". So I don't understand why we need a "ch" type.
Thanks in advance!
Hai Long
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Received on Wed Jun 29 2011 - 17:00:03 PDT
