The logarithmic term is again dominating. The sign of the interaction gives attraction or repulsion for the winding numbers + π π / 3 and − − π π / 3 of the five- and seven-folded disclinations in a way that charges with opposite sign have attraction. The overall strength is given by the stiffness against twist. The coupling constant F A is called Frank's constant, following the theory of liquid crystals. E s is the discrete energy of a dislocation to dissociate into two disclinations. The squared distance of two disclinations can be calculated the same way, as for dislocations, only the prefactor, denoting the coupling constant, has to be changed accordingly. It diverges for F A ⋅ ⋅ π π 36 = 4 . The system is molten from the hexatic phase into the isotropic liquid, if unbound disclinations are present. This transition temperature T i is given by Frank's constant: