On the theory of double Ising chains. Model in a zero external field

The free energy and initial magnetic susceptibility of a double Ising chain are calculated with account of diagonal interactions in a cell, four-particle interactions, and also under the assumption of distinct, generally speaking, g-factors of particles belonging to the different one-dimensional chains from which the double Ising chain is constructed. The temperature behavior of the specific heat and the initial magnetic susceptibility is studied by using an electronic computer. Simple asymptotic dependences for the specific heat and the susceptibility are obtained in the high temperature limit.