Re: [AMBER] How do I know if QM is working in sander.MPI?

From: Jason Swails <>
Date: Thu, 21 Nov 2013 09:53:05 -0500

On Thu, 2013-11-21 at 09:00 -0500, Brian Radak wrote:
> I always did find that to be the most frustrating of mistakes...
> Would it be possible to add a warning if a qmmm namelist is present but
> ignored (*i.e.* ifqnt = 0)?

If ifqnt is explicitly set to 0 in the input file, I don't think any
warning should be issued---it is quite easy to imagine use cases when a
user would want to disable QM/MM and _not_ delete their entire QM/MM

It's pretty easy to add a warning if ifqnt is not set in &cntrl but
&qmmm is present. Perhaps this is not going far enough, though. The
available options for when &qmmm exists but ifqnt is not set are:

1) Just print a warning to the mdout but carry on with no change to the
existing default behavior.

2) Quit with an error, forcing users to either set ifqnt=0 or delete the
&qmmm namelist to disable QM/MM.

3) Change the default behavior so that the default value of ifqnt is 1
if &qmmm is present and 0 otherwise.

Personally I think (2) is the best option, since it obeys the principle
of least astonishment in my opinion and doesn't risk a guess where
ambiguity exists.

I've implemented (1) already, but it's trivial to change it to either 2
or 3.


Jason M. Swails
Rutgers University
Postdoctoral Researcher
AMBER mailing list
Received on Thu Nov 21 2013 - 07:00:03 PST
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