Bonding in a Cu (001) monolayer

Results of a first-principles all-numerical linear variational energy-band calculation are presented for a Cu (001) monolayer. The electronic structure is discussed in terms of the changes in $d$ bonding which accompany the descent in symmetry in going from the bulk to the surface. The relation of the splittings and ordering of the levels to those of the bulk follow expectations based on simple $d$-bonding considerations. Results are compared with those from other studies and some discrepancies among earlier works are resolved.