Re: Tcl forces

From: Axel Kohlmeyer (
Date: Fri Oct 16 2009 - 16:21:04 CDT

On Fri, 2009-10-16 at 16:06 -0400, Myunggi Yi wrote:
> Dear NAMD users,
> I want to run a simulation with tcl forces.
> I want to use vecnorm, veccross, veclength, vecdot, vectrans, etc
> inside the "calcforces".

> Can I use all of these defined in VMD?

not necessarily. NAMD and VMD don't share any runtime code,
but it is likely that somebody working on NAMD has copied
some of the convenience routines over. you have to check, though,
whether the semantics are identical.

> Where can I check what vector routines are allowed in NAMD tclforces?

this is much more a tcl question than a namd question.

the tcl command to list available commands is: info commands.

so just write a small input file that contains:

info commands vec*

and run a serial namd executable on it, and it should print out
which commands starting with vec are supported.

and then run: vmd -dispdev text -e on it and you can see what
is defined in VMD.

my guess is that there are more vector commands in VMD then
in NAMD, but you may get lucky that all what you need is
available. also, you can easily define your own (for as long
as it is pure Tcl code).

> --
> Best wishes,
> Myunggi Yi
> ==================================
> 91 Chieftan Way
> Institute of Molecular Biophysics
> Florida State University
> Tallahassee, FL 32306
> Office: +1-850-645-1334

Dr. Axel Kohlmeyer 
Institute for Computational Molecular Science
College of Science and Technology
Temple University, Philadelphia PA, USA.

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