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Short helpfile for action MEMFUSIONP
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The input trajectory can be in any of the following formats: 

              UMEMBRANE - all the beads of the upper membrane. For more information 
                          on how to specify lists of atoms see \ref Group 
              LMEMBRANE - all the beads of the lower membrane. For more information 
                          on how to specify lists of atoms see \ref Group 
                  TAILS - all the tail beads of the system. For more information on 
                          how to specify lists of atoms see \ref Group 

The following arguments are compulsory: 

                  NSMEM - the number of slices of the membrane fusion cylinder in 
                          such a way that when the bilayers are flat and parallel the CV 
                          is equal to 0.2. 

In addition you may use the following options: 

  NUMERICAL_DERIVATIVES - ( default=off ) calculate the derivatives for these 
                          quantities numerically 
                  NOPBC - ( default=off ) ignore the periodic boundary conditions 
                          when calculating distances 
                  DSMEM - ( default=0.1) thickness of the slices of the membrane 
                          fusion cylinder. 
                   HMEM - ( default=0.25 ) parameter of the step function θ(x,h) for 
                          the membrane fusion. 
                RCYLMEM - ( default=1.75 ) the radius of the membrane fusion 
                          cylinder. 
                ZETAMEM - ( default=0.5 ) occupation factor. 
      ONEOVERS2C2CUTOFF - ( default=500 ) cut off large values for the derivative of 
                          the atan2 function. 
                   XCYL - X coordinate of the fixed cylinder, if not present this 
                          will be calculated. 
                   YCYL - Y coordinate of the fixed cylinder, if not present this 
                          will be calculated. 


