2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/125787The method has been developed to calculate effects of polarization not only for a atomic core in a field of valent electron, but also polarization of atom as a whole in the electron-hole formalism. A secondary quantized density matrix for many-electron system was used to find the Green function of a quasiparticle and its effective mass due to many-particle effects.14 pagesQuantum Physicstext