force non-bonding between two atoms

[ripes72]

Hi,

I am trying to explore a zwitterionic structure obtained after O-C bond breaking.
This should be a reactive intermediate of a reaction. I could isolate it after a bond length scan,
However, when I try to further explore this zwitterion (I would be interested in its conformational entropy),
unavoidably the bond is reformed and I get a topology change error.
Is there a way to add a constraint specifying that a certain bind should NOT be formed?

Thanks