# Hard hexagons: exact solution

@article{Baxter1980HardHE, title={Hard hexagons: exact solution}, author={Rodney J. Baxter}, journal={Journal of Physics A}, year={1980}, volume={13} }

The hard-hexagon model in lattice statistics (i.e. the triangular lattice gas with nearest-neighbour exclusion) has been solved exactly. It has a critical point when the activity z has the value 1/2(11+5 square root 5)=11.09017..., with exponents alpha =1/3, beta =1/9. More generally, a restricted class of square-lattice models with nearest-neighbour exclusion and non-zero diagonal interactions can be solved.

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