Structure of essential spectrum and discrete spectra of the energy operator of five-electron systems in the Hubbard model. Fourth quartet state

We consider the energy operator of five-electron systems in the Hubbard model and investigate the structure of essential spectra and discrete spectrum of the system in the fourth quartet state of the system. We show that the essential spectrum of the system in fourth quartet states is the union of at most seven segments, and discrete spectrum of the system is at most one point.