Re: How to obtain the system force on a fixed atom

From: Jérôme Hénin (
Date: Wed Dec 16 2009 - 12:01:33 CST

2009/12/16 Roman Petrenko <>:
> Dear Mary,
> why should it be non-zero? what does newton's first law say?

That's just a technicality, but in NAMD parlance, the "total force" or
"system force" should be the force from the force field, not including
the constraint force. So Newton's law says that the "total" force is
exactly the opposite of the constraint force, so that the *total*
force is zero :-)


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