[gmx-users] puzzling about ffnonbonded.itp
Mark.Abraham at anu.edu.au
Mon Sep 3 15:21:06 CEST 2012
On 3/09/2012 6:02 PM, Wu Chaofu wrote:
> Dear gmxers,
> While I try to make one customed force field by studying some existing
> force fields, I find that bond_type and at.num defining [atomtypes ]
> in the ffnonbonded.itp are included in some force fields (i.e.
> oplsaa), but not in other force fields (i.e gmx). I wonder how gmx
> identifies the difference and choose the correct parameters from them.
> Could you please expain this in details? Thank you very much for any
Not sure which part of these issues you're concerned about. Different
force fields work differently. Few of these fields are actually relevant
(e.g. charge never is, in practice), some get over-ridden some times.
grompp has a bunch of magic scanf() format strings that work out what is
in each field and dispatches the information to the data structure
correctly. In practice, you should probably pick an existing force field
as a model and follow its format.
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