targetCenters in Umbrella Sampling

From: Olya Kravchenko (
Date: Wed Aug 24 2016 - 17:50:36 CDT

Hi all,

just another question about umbrella sampling calculations for ion
permeation and colvar input file.
The harmonic restraint part for my input file looks like this now:

harmonic {
          colvars test
          centers 134.0
          forceConstant 5.0
          targetCenters 108.0
          targetNumSteps 1

I would like to measure PMF for the ion moving between 134 and 108. Do
I understand it correctly that I have to use 108 for targetCenters?
When I use 108, namd quits. But when I use smaller numbers (up to 54)
it runs normally. Why would that be the case?


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