expandBoundaries and multiple walker metadynamics

From: Jeff Wereszczynski (jmweresz_at_mccammon.ucsd.edu)
Date: Mon Oct 01 2012 - 13:52:53 CDT

Hello,

I'm trying to run multiple walker metadynamics, however I keep getting the
following error:

colvars: Error: expandBoundaries is not supported when using more than
one replicas; please allocate wide enough boundaries for each colvarahead
of time.

While this sounds straightforward, I've explicitly turned off both
expandBoundaries and useGrids in my colvars file. Here is the colvars file:

-----------------------------------------------------------------------------------
colvar {
  name rgyr
  expandBoundaries off
  width .1
  lowerboundary 0
  upperboundary 15
  lowerwallconstant 1
  upperwallconstant 1
  gyration {
      atoms {
         atomsFile rgyr.pdb
         atomsCol O
      }
  }
}
metadynamics {
        name metad
        colvars rgyr
        hillWeight .2
        hillWidth 10
        newHillFrequency 100
        usegrids false

        multipleReplicas on
        replicaID 01
        replicasRegistry replicas

}
-----------------------------------------------------------------------------------

And here is the relevant output in the NAMD log file:

colvars:
----------------------------------------------------------------------
colvars: Initializing a new collective variable.
colvars: # name = rgyr
colvars: Initializing a new "gyration" component.
colvars: # componentCoeff = 1 [default]
colvars: # componentExp = 1 [default]
colvars: # period = 0 [default]
colvars: # wrapAround = 0 [default]
colvars: Initializing atom group "atoms".
colvars: Atom group "atoms" defined, 21 initialized: total mass =
264.19.
colvars: All components initialized.
colvars: # width = 0.1
colvars: # lowerBoundary = 0
colvars: # lowerWallConstant = 1
colvars: # lowerWall = 0 [default]
colvars: # upperBoundary = 15
colvars: # upperWallConstant = 1
colvars: # upperWall = 15 [default]
*colvars: # expandBoundaries = off
*colvars: # extendedLagrangian = off [default]
colvars: # outputValue = on [default]
colvars: # outputVelocity = off [default]
colvars: # outputSystemForce = off [default]
colvars: # outputAppliedForce = off [default]
colvars:
----------------------------------------------------------------------
colvars: Collective variables initialized, 1 in total.
colvars:
----------------------------------------------------------------------
colvars: Initializing a new "metadynamics" instance.
colvars: # name = metad
colvars: # colvars = { rgyr }
colvars: # hillWeight = 0.2
colvars: # newHillFrequency = 100
colvars: # hillWidth = 10
colvars: # useGrids = off
colvars: # multipleReplicas = on
*colvars: Error: expandBoundaries is not supported when using more than
one replicas; please allocate wide enough boundaries for each colvarahead
of time.
*colvars: If this error message is unclear, try recompiling with
-DCOLVARS_DEBUG.
FATAL ERROR: Error in the collective variables module: exiting.

For clarity, I've bolded the lines that say expandBoundaries is off and the
error message telling me it isn't. I've tried recompiling NAMD with the
DCOLVARS_DEBUG flag on, but that didn't provide any more helpful
information. I also went through the source and found that this error is
triggered by the expand_grids flag, but I can't figure out where that is
being set in the code. Any suggestions on this would be greatly
appreciated!

Also, while I'm asking questions, just for my own sanity have the multiple
walker + well tempered metadynamics options been tested together? I assume
there are no major issues I should look out for?

Thanks, 

-- 
Jeff Wereszczynski
Postdoctoral Scholar
University of California, San Diego
http://mccammon.ucsd.edu/~jwereszc

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