Distribution of zeros of the partition function of the antiferromagnetic Husimi-Temperley model I

(For pt. I, see abstr. A5084 of 1973). The author determines the distribution of zeros of the partition function in the antiferromagnetic case. A principle to determine the limiting locus of zeros of the partition function in the complex fugacity plane has been proposed and the locus was obtained for the antiferromagnetic Husimi-Temperley model. The principle states that the locus is obtained as the place where the real parts of two branches of chi (z) ( identical to analytic continuation of lim 1/N ln Z, where Z is the partition function), whose real parts are the largest and the next largest among several branches, take the same value. The proof of the principle is given for the AHT model. The principle is intuitively plausible and it is suggested that it may work for quite a wide class of models.