Extending multiple histogram reweighting to a continuous lattice spin system exhibiting a first-order phase transition.

We present extensive Monte Carlo simulations on a two-dimensional XY model with a modified form of interaction potential. Thermodynamic quantities other than energy, specific heat, etc. (such as magnetization, susceptibility, and fourth-order cumulant of magnetization) are obtained using multiple histogram reweighting of the data obtained from the simulations. We employ an approach which eliminates the need to construct two-dimensional histograms. This approach makes judicious use of computer memory as well as CPU time. Lee-Kosterlitz's method of finite size scaling for a first-order transition and analysis using Binder's cumulant method allow us to make an accurate determination of the transition temperature.