From: JC Gumbart (
Date: Sun Oct 18 2020 - 18:37:03 CDT


In CHARMM, non-polar hydrogens are assigned 0.09 by default, and the associated carbons are often made -0.18 or -0.27 accordingly. Going beyond this, I recommend looking at published examples, e.g., the CHARMM36 lipid force field, for ideas: <>


> On Oct 13, 2020, at 6:55 PM, Lokendra Poudel <> wrote:
> Hi Everyone!
> I am generating a CHARMM force field for a drug from VMD's FFTK. This drug is extremely hydrophobic/insoluble in water. Is the step of generating water interaction of QM data then charge optimization necessary or not to my molecules? since it is extremely hydrophobic. please advise me.
> Best regards
> Lokendra Poudel, PhD