We present the exact solution to a one-dimensional multicomponent quantum lattice model interacting by an exchange operator which falls off as the inverse-sinh-square of the distance. This interaction contains a variable range as a parameter, and can thus interpolate between the known solutions for the nearest-neighbor chain, and the inverse-square chain. The energy, susceptibility, charge stif...

We present a set of exactly solvable fermionic spinS for the classical Ising model on a square-type lattice including a quartic interaction term in the Hamiltonian, using an auxiliary mixed fermionic spin-(S,1/2) square-type lattice with only first nearest-neighbor interaction. The particular properties of the mixed lattice, associated to the fermionic mixed spin-(S,1/2), allow us to map this s...

Quantum model of interacting " strings " on the square lattice Abstract The model which is the generalization of the one-dimensional XY-spin chain for the case of the two-dimensional square lattice is considered. The subspace of the " string " states is studied. The solution to the eigenvalue problem is obtained for the single " string " in cases of the " string " with fixed ends and " string "...