COM position

From: Mauricio Carrillo Tripp (
Date: Fri Jul 02 2004 - 16:54:01 CDT

Hi all, I'm not sure this went through so I'm sending it again with more

is there a way to keep the position of the system's center of mass
fixed at a certain point (e.g. origin) ?
is there a command to accomplish this or do I have to write a script? How
do I do it?

Reading the manual I found in section 6.7.3 and 6.7.6 (Options for
restraints and Examples, Fixed restraints page 80) that I can do something

urestrain {
  posi group {(*,*,*)} kf=20 ref=(0,0,0)

I'm not sure about the *'s though, should I use {all} instead?
Would this work?

Afterall, all I want to do is to keep the COM from moving in the Z

Thanks for any help

Mauricio Carrillo Tripp
Chemistry Department
Wabash College

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