[gmx-users] Difference between charmm22 and charmm27 force fields.

[Dawid das]

Dear gromacs experts,

I have a question not related directly to gromacs program.
Is there difference in parameters for protein (aminoacids) atom types
between charmm22 and charmm27? In other words, may I use parameters for
charmm22 for a new non standard aminoacid residue if I use charmm27 for all
other aminoacids?