Topological aspect of disclinations in two-dimensional melting
  By using topological current theory, we study the inner topological structure of disclinations during the melting of two-dimensional systems. From two-dimensional elasticity theory, it is found topological currents for topological defects in homogeneous equation. The evolution of disclinations is studied, and the branch conditions for generating, annihilating, crossing, splitting, and merging of disclinations are given. 
Wei-Kai Qi, Tao Zhu, Yong Chen, and Ji-Rong Ren