Density of states of a two-dimensional XY model from the Wang-Landau algorithm.
Using the Wang-Landau algorithm combined with the analytic method, the density of states of a two-dimensional XY model on square lattices of sizes 16x16, 24x24, and 32x32 is accurately calculated. Thermodynamic quantities, such as internal energy, free energy, entropy, and specific heat are obtained from the resulted density of states by numerical integration. It is found that both the density of states and the extensive thermodynamic quantities obey the scaling law. From the entropy curve, symptoms of phase transition are observed. A general method of calculation of the density of states of continuous models by simulation combined with analytical method is proposed.
Xu
Jun
J
Institute of Theoretical Physics, Shanghai Jiao Tong University, Shanghai 200240, China.
Ma
Hong-Ru
HR