Phase Diagram of a 2D Vertex Model
  Phase diagram of a symmetric vertex model which allows 7 vertex configurations is obtained by use of the corner transfer matrix renormalization group (CTMRG), which is a variant of the density matrix renormalization group (DMRG). The critical indices of this model are identified as $\beta = 1/8$ and $\alpha = 0$. 
Hiroshi Takasaki, Tomotoshi Nishino, and Yasuhiro Hieida