[gmx-users] Transference of dihedral potentials between united atom and all-atom force fields

[Peter Stern]

No, of course not.  United atom potentials are optimized taking into account that the hydrogens are not included.  Think about it.  If you use the United atom dihedral potential in an all-atom force field you will also be adding to that all the dihedral potentials which include the hydrogen atoms.  Clearly this is not going to be the same for a particular C-C bond.

And in general, you cannot transfer parameters from one force field to another.  I think that has been emphasized repeatedly in this forum.

Regards,
Peter


Sent from my iPhone

On Jun 29, 2019, at 2:10 PM, Pragati Sharma <pragati2325 at gmail.com<mailto:pragati2325 at gmail.com>> wrote:

Hello gromacs users,

I have a query regarding transference of dihedral potentials between united
atom and all-atom force fields. Suppose, for a dihedral of four carbon
atoms in polybutadine (united atoms: CH2-CH=CH-CH2). Can I use the same
dihedral potentials or force constants for the same set of atoms in an
all-atom force field where carbon and hydrogens are treated separately
while keeping the potential functions same.

Thanks, Pragati
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