First-principles study of the adsorption of cesium on Si(001)(2×1) surface

Abstract

First-principles calculations based on density functional theory-generalized gradient approximation method have been performed on cesium adsorption on Si(001)(2 x 1) surface. The optimized geometries and adsorption energies have been obtained and the preferred binding sites have been determined for the coverage (Theta) of one monolayer and half a monolayer. At Theta = 0.5 ML the most stable adsorption site is shown to be T3 site. At Theta = 1 ML two Cs atoms are adsorbed at HH and T3 sites, respectively. It was found that the saturation coverage of Cs for the Si(001)(2 x 1)-Cs surface is one monolayer instead of half a monolayer. This finding supports the majority of experimental observations but does not support recent coaxial impact collision ion scattering spectroscopy investigations [Surf. Sci. 531, L340 (2003)] and He(+) Rutherford backscattering spectroscopy studies [Phys. Rev. B 62, 4545 (2000)]. Mulliken charge and overlap population analysis showed that the Cs-Si bond is indeed ionic rather than polarized covalent as generally assumed for alkali metal (AM) on Si(001)(2 x 1) surface. Geometrical structure analysis seems to have limitations in determining the nature of AM-substrate bond. We also found that the silicon surface is metallic and semiconducting for the coverages of 0.5 and 1 ML, respectively.

Functionalization of a GaSe monolayer by vacancy and chemical element doping

“…45 The electron structure calculations employing the density functional theory have been rapidly developed during the last decade and it has now become feasible to obtain quite high accuracy for a variety of systems. [46][47][48] The core electrons and the exchange-correlation energy are described by the projector augmented wave (PAW) potentials 49 and the generalized gradient approximation (GGA) with the Perdew-Burk-Ernzerhof (PBE) functional, 50 respectively. A vacuum region of 15 Å is used to ensure decoupling between neighboring slabs.…”

First-principles study of Sb adsorption on Ag(110)(2×2)

“…In the current work, we have performed a detailed study on the Sb-Ag(1 1 0) chemisorption system using periodic density functional theory (DFT) method. Such method has been demonstrated to be used for calculating the electronic and structural property of medium-sized systems with predictive accuracy [20][21][22][23][24][25][26][27]. The energetic and geometric properties of this system, surface relaxation of Ag(1 1 0) surface, and the diffusion behavior for Ag adatom jumping along the inchannel and cross-channel directions on the Ag(1 1 0) surface all have been reported.…”

Adsorption of Li on Cu(110): Density-functional calculations

“…Such method has been demonstrated to be used for calculating the electronic and structural property of medium-sized systems with predictive accuracy [8,9]. The preferred adsorption sites, optimized geometries, work function change, surface diffusion and surface information energy all have been presented and analyzed.…”