We analyze the critical point and study the nonuniversal peculiarities occuring in the temperature dependence of the specific heat for a sequence of the exactly solvable highly decorated two-dimensional triangular-type ferromagnetic Ising models with a complicated (fractal-type) inherent...

A general class of model systems of quantum statistical mechanics representing substance coupled to a discrete spectrum of a quantized boson field is studied on the basis of the “approximating (trial) Hamiltonian” method. Proof is presented that the models under investigation are exactly...