Acta Physica Polonica A vol:92 issue:2 pages:453-456
The phase diagram of the Askhim-Teller model in two dimensions is determined. Numerical calculations are performed for the simple square L x L lattice using transfer matrix technique. Exploiting finite-size scaling all unknown critical lines were obtained with good accuracy. An extended version of the Ashkin-Teller model is also considered within the molecular field renormalization group method and the critical surface for three-parameter odd-parity Hamiltonian is calculated.