[gmx-users] grompp with cg does have problem!

David Mobley dmobley at gmail.com
Thu Dec 15 17:18:34 CET 2005


I've had this same problem anytime I try to use CG to minimize my
system, so I've always just used L-BFGS or "steep" instead (they work
fine). I'm not imposing any constraints (constraints= none), but it
still complains that I can't use CG with constraints, so I haven't the
foggiest idea what it's complaining about. I can provide mdp, topology
and .gro files to reproduce this if you'd like. I suspect that either
(a) the routines for CG consider something *else* a constraint (i.e.
aside LINCS constraints, etc.), in which case it's possible we have
that turned on without being aware of it,  or (b) there is a bug in
the setup for CG.


On 12/14/05, Mark Abraham <Mark.Abraham at anu.edu.au> wrote:
> Samuel Silva Pita wrote:
> Hi Samuel,
>  > Subject: grompp with cg does have problem!
> When you are relatively inexperienced, seeking a solution to a problem
> from a mailing list that includes developers of a piece of software, you
> would be well advised not to imply that the problem is with the software
> (rather than your use of it), without serious evidence.
> > deuar GMXers,
> > my system doesn't work when i do energy minim. with cg after doing it using steep. The following message are showing:
> > "processing coordinates...
> > double-checking input for internal consistency...
> > ERROR: can not do Conjugate Gradients with constraints (201522)"
> >  I set in my .mdp not use constraints (constrainsts= none) and my water model is SPC216.
> > Can anyone help me?
> Read the CG section of the manual to see if you need to be doing CG here.
> In my opinion, the probability is quite high that you are implying
> constraints somehow. Check your output from (for example) pdb2gmx in
> detail - it gives a lot of information about what it is doing that
> people don't bother to read.
> Mark
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