First-principles study of the lattice dynamics of c(2 x 2)-CO on Cu(001)

作者：Ortigoza Marisol Alcantara^*; Rahman Talat S; Hield Rolf; Bohnen Klaus Peter

来源：Journal of Physics: Condensed Matter , 2008, 20(22): 224009.

DOI：10.1088/0953-8984/20/22/224009

The density-functional perturbation theory formalism is applied to investigate the dynamics of c(2 x 2)-CO/Cu(100), using both the local (LDA) and the generalized-gradient (GGA) density approximations through the Hedin-Lundqvist and the Perdew-Burke-Ernzerhof functionals, respectively. In the framework of the mixed basis pseudopotential approach, GGA reproduces notably well helium atom scattering (HAS) data for the frustrated translation (FT) mode and hence points to a harmonic nature of the Cu-C bond. LDA, on the other hand, is found to lead to instabilities of the FT mode inside the surface Brillouin zone (SBZ). The C-O internal stretch mode disperses in the two-dimensional SBZ by similar to 10 meV along the Delta direction. The Cu-CO stretch mode involves a significant contribution from first-layer Cu atoms. The frustrated rotation and FT modes disperse slightly and have their degeneracy removed by similar to 1 meV and similar to 3 meV, respectively, along the Sigma direction. The latter is in quantitative agreement with HAS data.

• 出版日期2008-6-4