Question about Coplanar Constraints and Improper Dihedral Angles

[Conor Abraham]

Hi Gary,

I have been trying to apply the CHARMM46 forcefield in Browndye, but am hitting a roadblock with the improper dihedral angles. So far, I have attempted to replace them with coplanar restraints, but Browndye terminates with "constraint initialization failed". My best guess is that this is happening because some atoms are involved in multiple improper dihedrals. Is this what's happening? Do you have any recommendations on how to go about applying the improper dihedrals without majorly impacting the forcefield?

Once again, thanks in advance for your help!

Best,

Conor

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Conor B. Abraham

Ph.D. Candidate, Straub Group

Boston University Department of Chemistry