Re: [AMBER] Changing NMR restraint weights

From: David A Case <>
Date: Mon, 13 Jul 2015 09:52:04 -0400

On Fri, Jul 10, 2015, Oliver Grant wrote:
> *If you wish to include weight changes but have no internal constraints,
> set nmropt=1, but do not include a*
> *DISANG line in the file redirection section.
> It's telling me to put the &rst namelists in the DISANG file, but don't
> redirect to the DISANG file.

No: it is telling you to set nmropt=1, and not to include a reference
to a DISANG file in the redirection section. If you don't have any internal
restraints, you will have no &rst namelists, and hence no need for a DISANG

> I want weight changes and have no internal constraints. But if I can't
> redirect to my DISANG file and can't include the &rst namelists in the mdin
> file, how do I use weight changes?

Weight changes do *not* involve &rst namelists, so I think what is said above
makes sense. Put the weight change change cards in the mdin file, and don't
reference any DISANG file. (However, it seems like you actually *do* have
restraints, so I am a bit confused here.

> I can get the restraints applied, but not the weights. The outfile is
> misleading. It prints the weight changes I want, but in step 0 they are not
> applied.

Step 0 may indeed be special. Try this: run a 1 step MD with no restraints;
then do a restart calculation from that, using the restraints. That will
start at step 1, and may do what you want.

I'm a little confused, however, since the REST weight change command doesn't
make any sense if you don't have distance (or other NMR-like) restraints.

I also don't remember seeing the problem before...I'll have to check some
older outputs.


> Begin reading energy term weight changes/NMR restraints
> TEMP0 1 900 5.000000 25.000000 0 0
> TEMP0 901 1000 25.000000 25.000000 0 0
> REST 0 100 0.000000 0.000000 0 0
> REST 101 1000 0.010000 1.000000 0 0
> No valid redirection requests found
> Number of restraints read = 7
> Done reading weight changes/NMR restraints

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Received on Mon Jul 13 2015 - 07:00:02 PDT
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