Structural and vibrational properties of added-row reconstructions on O/Cu(110) and O/Ag(110) surfaces

The geometry and vibrational frequency of (2 x 1) and (4 x 1) reconstructed structures of O/Cu(110) and O/Ag(110) systems have been calculated using a first-principles method. The calculated frequency shift between (2 x 1) and (4 x 1) is ca 1 meV on both copper and silver surfaces, being consistent with experimental values obtained so far. In contrast to a prediction by Schimizu and Tsukada [Surf. Sci, 295 (1993) L1017], we have found that the difference in the local structure between (2 x 1) and (4 x 1) is considerably small, indicating surface stress plays only a minor role in the frequency shift of oxygen vibration. The estimated effective charge on oxygen atom is consistent with the HREELS value reported by Vattuone et al. [Surf. Sci. 369 (1996) 336], (C) 1999 Elsevier Science B.V. All rights reserved.