Partition function zeros for the two-dimensional Ising model V

The boundaries of regions containing complex temperature zeros of the partition function of the two-dimensional Ising model on partially anisotropic triangular lattices are investigated in detail. A “diagonal” symmetry of one of the boundaries on lattices with one “odd” and two equal “even” interactions is accounted for. A bifurcation of the other boundary at the imaginary axis is observed (for the two examples considered) on lattices with all “odd” interactions. An explanation of this bifurcation is provided. The locations of pure imaginary boundary points, and the end-points of lines of pure imaginary zeros, when present (on lattices with all “odd” interactions), have been related to the critical and disorder point equations.