colvarsTrajFrequency     100
colvarsRestartFrequency  100

colvar {
   name COMDistance
  
   width 0.1

   lowerboundary 0.0
   upperboundary 0.5

   lowerWallConstant  100.0
   upperWallConstant  100.0

   distance {

      group1 {
         atomnumbers { 43 }
      }
      group2 {
         atomnumbers { 1    4    5    8   11   12
                       15   18   19   22   25   26
                       29   32   33   36   39   40 }
      }
   }
}