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Adsorption energetics, structural and vibrational properties of the Cu(001)–c(2×2)–CO system are studied with periodic slab calculations within density functional theory in the local density (LDA) and generalized gradient (GGA) approximations by using ultrasoft pseudopotentials. The recent expression of Perdew, Burke, and Ernzerhof (PBE) has been used as the GGA functional [Phys. Rev. Lett. 77, 3865 (1996)]. The fully relaxed geometry of the system is determined for different adsorption sites of the CO molecule; unlike LDA, PBE-GGA predicts correctly the on-top adsorption site of the molecule. C–O and Cu–CO bond lengths, stretching frequencies, Cu-layer displacements, chemisorption energies, and work functions are computed under both approximations and are compared to the experimental values. LDA gives accurate values for the C–O equilibrium distance and the corresponding stretching frequency, while PBE-GGA better describes the adsorption bond and all the remaining properties.

The atomic structure of the Pd(110)-c(4 × 2)-benzene system has been determined by means of ab initio slab calculations. A C2 low-symmetry equilibrium configuration is predicted. The corresponding azimuthal angle θ ∼ 11 • of the adsorbed molecule is partly due to lateral interactions. The aromatic ring looses planar geometry and the C−H bonds bend away from the metal. STM images calculated for the C2 configuration are compatible with recent experimental data.

The origin of electronic states localized at ZnSe/Ge (110) interface is investigated by means of ab initio pseudopotential calculations. Some selected interface configurations are considered, one corresponding to the abrupt interface and others corresponding to partially disordered interfaces, with Zn-Ge or Se-Ge swaps. Remarkably, the existence of interface electronic states within the heterojunction band gap critically depends on the atomic-scale morphology of the interface: unlike the abrupt case, disordered interfaces exhibit localized states extending over the whole interface Brillouin zone. The presence of interfacial density of states, experimentally detectable, is therefore an indication of disorder and atomic interdiffusion.

The magnetization of the Ni͑110͒ surface is explored as a function of the CO coverage by means of periodic slab calculations within density-functional theory. The in-plane inspection of the spin density corresponding to the surface layer exhibits a CO-induced decrease in the Ni-atom magnetic moments that is limited to the atoms directly involved in the chemisorption bond. This decrease is due to interactions between the metal states and the CO orbitals that increase the population of the spin-down metal states within the outermost layer and decrease that of the corresponding spin-up ones.