[gmx-users] Fatal error: Unknown bond_atomtype cn9 in Charmm27

[Mijiddorj Batsaikhan]

Dear gmx users,

I am using gromacs-v5.1 with charmm27 force field that extended by
swissparams D amino acids.

I got a following error.

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Fatal error:
Unknown bond_atomtype cn9
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I searched some solutions, but there is no clear solution.
I also checked in atomtype.atp, etc., I could not find cn9, There are all
CN9.

How can I fix this error? please advice me for modification of FF.

Best regards,

Mijiddorj