Broad histogram method for multiparametric Hamiltonians

We extended the Broad Histogram Method in order to obtain spectral degeneracies for systems with multiparametric Hamiltonians. As examples, we obtained the critical lines for the square lattice Ising model with nearest- and next-nearest-neighbor interactions and the antiferromagnetic Ising model in an external field. For each system, the entire critical line is obtained using data from a single computer run. We also discuss the accuracy and efficiency of our method.