Abstract
The linear combination of muffin-tin orbitals technique has been used to calculate the effect of overlayers of O and Na on Ni(001) electronic-energy levels. We find that both Na and O induce surface states in the sd gap with the density and energies depending on the overlayer separation d. The peak observed experimentally at -0.4 Ry and O on Ni is due to nonbonding oxygen states as originally interpreted by Hagstrum and Becker.