Progress of Theoretical Physics
An Energy Curve Family of a Semi-Infinite Lattice and the Transition Point in the Potts Model
Hiroshi Katsumori, Shingo Ohya
Abstract
An energy curve family for a semi-infinite square lattice (l × ∞) of the q-state Potts model with periodic boundary conditions has an l-independent common fixed point, which gives the exact critical values of the coupling parameter K = J/kJ and the internal energy E(K), as a natural consequence of the self-dual property of the model. An energy curve intersection procedure (ECIP) is proposed to find the critical properties of the Potts model through numerical investigation of the transfer matrix. The ECIP shows that the lattices (l × ∞) for two different small values of l can reproduce the transition temperature and the critical internal energy of the bulk lattice (∞ × ∞) without use of the duality argument. As an applicable example of the ECIP, a semi-infinite simple cubic lattice (l × m × ∞) of the Potts model is preliminarily studied to obtain approximate critical quantities of the layer lattice (l × ∞ × ∞). A brief comment on the specific heat exponent μ estimated using the ECIP is added.