From: yanxiao han (
Date: Sat May 21 2016 - 12:51:19 CDT


I downloaded a PDB file(3cna) from pdb data bank, I try to get the force
field parameter by using force field toolkit(fftk).

I use "par_all27_prot_lipid.prm" and "par_all36_pro.prm" as the associated
parameter files. After analyze, it showed half dihedrals parameters are
missed, while all the bonds and angles can be found in the two associated

My question is how can I find the missed dihedrals parameters which are not
in the associated parameter files?

I try different version of reference parameter files of charmm, still can't
find the missed diherals.

If anyone can give me some guide?

Thanks so much!