Maximum in PES scans...



I need to clarify this email:
 In the _dissociation_ of a diatomic molecule, there is sometimes a
 maximum along the dissociation coordinate. I am observing this in a
 relaxed PES scan of a tetra-atomic dissociation. The dissociation goes
 to the proper, neutral fragments. The maximum, and all points beyond,
 have only one negative frequency, but I cannot rationalize the drop
 after the maximum.
   X
   X
   X
    X
    X             XXXX
    X            X    XXX
     X          X        XXXX
     X         X             XXXXXXXXXXXXXXXXXXXXXXXXX	(A+B)
      X       X
      X       X
       X     X
        X   X
         XXX
         (AB)
 Your help is appreciated!
 Roy Jensen