From: Hoang, Oanh Tu (
Date: Wed Jul 19 2023 - 08:15:22 CDT

Hello everyone,

I am trying to run constant pH MD with NAMD and I am following the tutorial (

I am already stuck at the first step when trying to source the namdcph.tcl file.

I get the following error


Expected a NAMD-Tcl interpreter - exiting.
Expected a NAMD-Tcl interpreter - exiting.
version conflict for package "psfgen": have 1.6.4, need 1.6.5
unknown namespace in import pattern "::namdcph::*"


I have tried and download several VMD versions but every VMD installation has the psfgen package 2.0 or 1.6.4 but I cant figure out how to get 1.6.5.

Second I wanted to ask if its possible to add a co-factor as titrable residues, when I have the parameters.