Re: tclforces: force not a vector

From: Peter Freddolino (
Date: Thu Jul 12 2007 - 07:24:37 CDT

please see the discussion from yesterday on this error. The same
solutions apply to your case.
Alternatively, if you don't mind using the cvs version of namd, you can
try the new extrabonds feature, which allows you to specify a file
containing dihedral restraints of the format

dihedral index1 index2 index3 index4 k theta0

To use this feature, set
extraBonds yes
extraBondsFile FILENAME
(where filename is the file containing your dihedral definitions)

in your config file.


maria goranovic wrote:
> While using a tclforces script to apply dihedral restraints, I get the
> following error after about 85000 steps of dynamics.
> #=============================================
> TCL: force not a vector
> FATAL ERROR: force not a vector
> while executing
> "addforce $id21 [vecscale $g5 $forcepsi]"
> (procedure "calcforces" line 78)
> invoked from within
> "calcforces"
> #==============================================
> The constraint script is attached. The attempt is to constrain the
> dihedral angles of the residues 19 and 197 to helical values.
> There is some discussion in the mail archive about the "force not a
> vector" error. What is confusing is why the error shows up only after
> 85000 steps, and not from the very beginning of the simulation ?
> Can someone please suggest a remedy ?
> -Maria.
> --
> Maria G.
> Technical University of Denmark
> Copenhagen

This archive was generated by hypermail 2.1.6 : Wed Feb 29 2012 - 15:44:57 CST