Block model for the XY-type Landau-Ginzburg-Wilson Hamiltonian with random temperature

► The phase fluctuation in disordered XY-type Landau-Ginzburg Hamiltonian is studied. ► For the modes with lowest eigenvalue, the systems is self-organized into blocks. ► The blocks are coupled as a XY model with random bond. ► The couplings obtained in this way agree with those by the domain wall method.