Abstract
The photoionization cross section (PICS) of Be from the ground state is studied with the saddle-point complex-rotation method for photon energies from 25 to 122 eV. A full-core plus correlation wave function is used for the ground state. For the resonances in the continuum, the energy and width for the singly core-excited Be $1s2s^2np\,^1P^o$ (n=2-6) are calculated to high precision. The PICS are studied with single open channel approximation as well as fully coupled open channels. The Auger decay branching ratios of these states are studied to check the spin alignment theory recently proposed by Chung. These results are compared with the previous theoretical and experimental data in the literature. Our Energy and width of $1s2s^22p$ are 115.513 eV and 36.6 meV and those of $1s2s^23p$ are 121.420 eV and 50.4 meV which agree with the experiment of Caldwell et al.