Account of electron scattering on many-particle clusters in strongly correlated systems. Electron spectra in the pairwise approximation in wannier and bloch representation

A generalized method for the calculation of electronic structure of disordered systems with strong electron correlations, based on Green's functions, is developed. It includes a recursive method for calculating the T -matrix of scattering on arbitrary many-particle clusters for the Green's function of the system, as well as extending this approach to the studying electronic spectra in both direct (Wannier) and reciprocal (Bloch) representations at a temperature of 0 K. The one-band Hubbard model, the correlated random field approximation, and the one-site approximation of coherent potential for the effective Hamiltonian are used in this method. The calculation of small parameter of the Green's function cluster expansion in direct and reciprocal representations shows its smallness for different parameters of b.c.c. alloys. This ensures the convergence of obtained recursive formulas for T -matrix of scattering on many-particle clusters and the applicability of pairwise approximation for T -matrix. The distributions of the electronic states in the reciprocal (as in the direct) representation demonstrate sensitivity to the changes in alloy characteristics and resulting atomic and magnetic orders, that can be used as a basis for the analysis of experimental data, for example, of positron spectroscopy, to study the defects, chemical composition and different correlations in systems. • Electronic structure of disordered systems with strong electron-electron correlations. • Green's function cluster expansion using recursive formula for T -matrix of scattering. • T -matrix takes into account multiple scattering on arbitrary many-particle clusters. • Joint method for calculating electronic spectra in Wannier and Bloch representations. • Application of electron spectra in Bloch space to positron spectroscopy data analysis.