[en] In the context of the pseudopotential approach, the atomic structure of four structural reconstructions of the Ga-enriched polar surface GaAs (001) is investigated. The geometry parameters of the surface structures of α-, β-, β2-, and ξ-GaAs (001)-(4 x 2) are determined. The electron structure and relative surface energies are calculated. The Cs absorption on the Ga-stabilized ξ structure GaAs (001)-(4 x 2) is considered. The highest absorption energy (2.57 eV) is obtained for the site S₅, which is characteristic of the increased coordination of the Cs atom by the As atoms. The analysis of the electron structure enabled the clarification of the mechanism of the Cs bond on the GaAs (001) surface and the variations introduced by this mechanism into the surface electron structure of the substrate