Yang-Lee Distribution of Zeros for a van der Waals Gas

The distribution of zeros of the grand partition function for a gas obeying van der Waals' equation of state (together with Maxwell's rule) is studied. For infinite temperature the zero distribution is located on part of the negative real axis, but with decreasing temperatures the distribution branches off the real axis circumventing the origin on both sides. Below the critical temperature the distribution forms a closed curve around the origin with a diameter decreasing exponentially to zero as T→0. An additional tail of the distribution remains on the negative real axis at all temperatures, but with a density of zeros going linearly to zero with T→0.