Spurious oscillations from local self-interaction correction in high energy photoionization calculations for metal clusters

We find that for simple metal clusters a single-electron description of the ground state employing self-interaction correction (SIC) in the framework of local-density approximation strongly contaminates the high energy photoionization cross sections with spurious oscillations for a subshell containing node(s). This effect is shown connected to the unphysical structure that SIC generates in ensuing state-dependent radial potentials around a position where the respective orbital density attains nodal zero. Non-local Hartree-Fock that exactly eliminates the electron self-interaction is found entirely free from this effect. It is inferred that while SIC is largely unimportant in high photon-energies, any implementation of it within the local frame can induce unphysical oscillations in the high energy photospectra of metal clusters pointing to a general need for caution in choosing appropriate theoretical tools.