The system enters the hexatic phase after the dissociation of dislocations. To reach the isotropic fluid, dislocations (5-7-pairs) have to dissociate into disclinations, consisting of isolated 5-folded and isolated 7-folded particles. Similar arguments for the interaction of disclinations compared to dislocations can be used. Again, disclinations can only be created as pairs due to topological reasons. Starting with the energy H c l i as function of distance between two disclinations one finds: