Second-order phase transition in the two-dimensional classical lattice Coulomb gas of half-integer charges

The second-order phase transition in the two-dimensional (2D) classical Cou lomb gas of half-integer charges on a square lattice is investigated by usi ng Monte Carlo simulations. Based on the finite-size scaling analysis, we e stimate the second-order phase transition temperature T-c and the static cr itical exponents beta and nu with a new numerical analysis method. More pre cise critical temperature T-c = 0.1311(2) and critical exponents beta/nu = 0.1152(12) and nu = 0.857(15) are obtained. The estimated value of nu indic ates that the charge lattice melting transition is different from the pure 2D Ising transition.