OVERLAYER AND INTERFACE RESONANCES AND BOUND-STATES AT PD AG(001) ANDAG/PD(001) SURFACES/

We have calculated the k(\\)-, symmetry-, and. layer-resolved density of states (DOS) at k(\\) = O for complete pseudomorphic monolayers of Pd on Ag(001) and Ag on Pd(001). For the xy and x(2) - y(2) subbands, which do not hybridize with any other low-lying orbitals, the resultin g DOS agrees quantitatively with that of a 1D-semi-infinite chain pert urbed only at the overlayer, i.e. terminal, site and at the interface, i.e. penultimate, site. The Pd overlayer presents a repulsive potenti al to the silver. This results in a surface (overlayer) state strongly bound above each subband, in pushing an existing surface (x(2) - y(2) ) state on pure Ag(001) further above the band and in converting an ex isting resonance (xy) into an interface bound state. The Ag overlayer on the other hand presents an attractive potential to the Pd, resultin g in a bound state below each subband and greatly weakened interface r esonances at the subband tops.