[gmx-users] Re: pull=constraint gives zero forces

Jaakko Uusitalo j.j.uusitalo at rug.nl
Tue Oct 9 08:57:44 CEST 2012

Hi Alex,

constraint pulling has a bug in 4.5.5, see: 
http://redmine.gromacs.org/issues/825. I'm guessing that's causing your 
problems. Fixing it is very easy (see the link) or you can also use an 
earlier version like 4.5.3 that works.


On 9.10.12 2:26 , Christopher Neale wrote:
> Please post your entire .mdp file and a snip of the output in your pullf and pullc files.
> (Your initial post on this topic was also missing these, although the text reads as if you intended to include them).
> I'll note that there are no forces when using constraints, so the fact that you get zero forces for a constrained run
> is not really surprising. I guess the thing is that it doesn't work to keep atoms in place for you,
> which we can help you with if you post more details.
> Chris.
> -- original message --
> Following up on this post. I've tried the same runs using version 4.0.7,
> which gave immediate segmentation faults. Not sure if this is a clue or a
> trivial consequence of switching versions, but there it is.
> Any other ideas why the pullf output just contains zeros?
> Cheers,
> Alex

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