  The classical two-dimensional anisotropic triangular nearest-neighbor Ising
(ATNNI) model is studied by the density matrix renormalization group (DMRG)
technique when periodic boundary conditions are imposed. Applying the
finite-size scaling to the DMRG results a commensurate-disordered (C-D) phase
transition line as well as temperature and magnetic critical exponents are
calculated. We conclude that the (C-D) phase transition in the ATNNI model
belongs to the same universality class as the ordered-disordered phase
transition of the Ising model.
