Six-state clock model on the square lattice: Fisher zero approach with Wang-Landau sampling

We investigate the six-state clock model with nearest-neighbor interactions on the square lattice. We obtain the density of states of the finite systems up to L=28 using the Wang-Landau sampling. With the density of states and the Fisher zero approach, we successfully find two different critical temperatures 0.632(2) and 0.997(2) for the clock model. It seems that this study supports the recent results by [Lapilli Phys. Rev. Lett. 96, 140603 (2006)] that the transitions are not of Kosterlitz and Thouless type.