The state-of-the-art ab initio calculations are performed to study the effect of surface-state electrons of Cu͑111͒ on electronic states in Cu chains. We reveal the existence of localized electronic edge states at energies close to the surface-state band edge of Cu͑111͒. These states are shown to be similar to the bound states at single adatoms on Cu͑111͒ recently detected by the low-temperature scanning tunneling microscopy ͓Limot et al., Phys. Rev. Lett. 94, 036805 ͑2005͒ and Olsson et al., Phys. Rev. Lett. 93, 206803 ͑2004͔͒.

The interplay between structure and magnetic properties of small cobalt clusters embedded in a Cu(001) surface is studied performing ab initio and tight-binding calculations in a fully relaxed geometry. We reveal that, despite the small macroscopic mismatch between Co and Cu, the strain relaxations at the interface have a profound effect on the structure of the clusters and the substrate. The physical mechanism responsible for the strain relaxations in embedded clusters is related to the size-dependent mesoscopic mismatch which has been recently introduced to understand homo-and heteroepitaxial growth at the mesoscale [O. V. Lysenko et al., Phys. Rev. Lett. 89, 126102 (2002)]. We show that the atomic relaxations strongly reduce the magnetic anisotropy energy (MAE) and the orbital magnetic moments of embedded clusters. The largest MAE of about 1.8 meV is found for a single Co atom in the Cu(001) surface. A strong enhancement of the spin magnetic moments in embedded clusters as compared to a single atom of Co incorporated in the Cu(001) surface is found. Magnetic properties of embedded and supported clusters are compared. While in supported clusters the MAE is strongly enhanced at the edge atoms, the immersion of the cluster into the surface and atomic relaxations make the distribution of the local MAE contributions and orbital-moment values almost homogeneous.

Ab initio studies reveal the interplay between structure and quantum effects in atomic-sized Cu nanocontacts. Our approach is based on density functional theory within the frame of a Korringa-Kohn-Rostoker Green's function method. We present evidence that the electronic structure of nanocontacts during stretching is governed by quantum-mechanical resonances. Our results indicate that the quantum size-effects have a profound effect on electronic states of contacts before breaking.

State of art ab initio calculations in a fully relaxed geometry reveal the interplay between structure and magnetism in atomic-sized nanocontacts. Our studies for Co, Pd, and Rh nanocontacts sandwiched between Cu electrodes demonstrate that atomic relaxations strongly affect magnetic states and lead to an inhomogeneous distribution of magnetic moments on atoms of nanocontacts. Stable ferromagnetic solutions with large magnetic moments are found for Co and Rh nanocontacts before breaking of the contact. We predict that Pd nanocontacts are nonmagnetic before the breaking, however, the energy difference between ferromagnetic and nonmagnetic states is only 6 meV. Our results suggest that variations in the structure, temperature or applied field could lead to transitions between magnetic and nonmagnetic states in Pd nanocontacts.