Kheifets, AnatoliBray, Igor2015-12-132015-12-131050-2947http://hdl.handle.net/1885/94691The integrated and fully differential cross sections of the DPI (double photoionization) of beryllium (Be) in the frozen-core approximation were presented. The photon-energy dependence of the total ionization excitation and the double ionization cross sections in Be resembled that of helium (He). Various singly and doubly ionized channels were represented by a near-complete set of negative and positive energy pseudostates.Keywords: Approximation theory; Atoms; Beryllium; Electrons; Ground state; Hamiltonians; Helium; Photons; Vectors; Double photoionization (DPI); Photoionization20022015-12-12