The Hartree-Fock method with orthogonality restrictions for doubly excited and ionized states

It is shown that the doubly excited and ionized states with vacancies in the K electronic shells can be considered within the framework of the same scheme on the basis of the asymptotic projection method proposed earlier. In contrast to the conventional methods, the electron detachment effect is achieved by imposing the requirement that the orbitals of the excited (hole) state be orthogonal to the orbitals of removed electrons. The solution of equations that determine the orbitals is implemented in terms of the conventional spin-unrestricted Hartree-Fock method with additional conditions that ensure the spin purity and provide a unique choice of the zero-order approximation in constructing the many-particle perturbation theory for taking into account the correlation effects. The performance of the method is demonstrated by calculating the excitation energies and ionization potentials corresponding to the removal of electrons from the inner K-shell.