Semigroup of projective transformations for averaging the Green's function of quasione-dimensional disordered systems

Semigroup of projective transformations for weakly interacting chains is suggested. The transition from one element of the semigroup to the next one is performed by means of increasing the size of reducing blocks within which the exact averaging of the Green function is made. The results of evaluations of the electron spectrum of the model of quasi-one-dimensional binary alloy with the diagonal disorder are presented. They demonstrate the rapid convergence of the method and the principal features of the statedensity due to increasing of the number of chains.