The ionization probability of an atom scattered from an atom adsorbed on a metal surface has been studied theoretically within the time-dependent Anderson-Newns model. The effect of the metal electron density of states, the band filling as well as the relative position of the scattered atom and adsorbed atom energy levels have been considered and the comparison with the results obtained for clean surfaces has been made.
We study an electron transport through a quantum dot in the presence of time-dependent fields. The dot is described by a single level and the intra-dot Coulomb interaction is introduced within the Hartree-Fock approximation. The external fields cause a time-dependent shift of the energy spectrum of the leads and quantum dot. We take into account the spin-polarized solutions for the quantum dot charge. We calculated the time dependence of the current and charge accumulated on the dot, the average current and charge vs. the source-drain and gate voltages in dependence on the Coulomb interaction strength and the frequencies and amplitude of the external fields.
The adsorption isotherms for Ising-Anderson type model Hamiltonian describing the chemisorbed system was calculated. The submonolayer coverage of the substrate surface was considered on the equal footing together with the electronic characteristics of the chemisorbed adatoms in a self-consisting manner. The resulting adsorption isotherms depend in explicit way on the electronic parameters describing the chemisorbed adatoms and substrate metal.
The influence of the dynamic hopping term included in the Newns-Anderson Hamiltonian on the electronic structure of the chemisorbed layer at different coverages rates is investigated. It is shown that this additional interaction can destroy the initial symmetry of the Newns-Anderson model or restore this symmetry in the initial negative asymmetric case. The coverage dependence of the adatom electron charge is also studied for the case of hydrogen chemisorption on a model transition metal surface.
A simple model describing resonant charge transfer between the free-electron metal surface and an atom colliding with it at some distance from another adsorbed atom is presented. The negative ionization probability of a scattered atom is studied within the time-dependent Anderson-Newns model and the time-evolution operator approach. With appropriate models for the considered system, the ionization probability is shown to oscillate with the distance between the adsorbed atom and the collision point of the scattered atom with the metal surface. These oscillations are results of the indirect interaction between the adsorbed and the scattered atoms due to the coupling of both atoms with the metal energy band.
We study the charge exchange in atom-metal collisions in the framework of the generalized time-dependent Anderson-Newns model. The electron correlations and correlated hopping are treated within the mean-field approximation. The resulting one-particle model with an effective spin-dependent atom-surface coupling is used to study the charge transfer in scattering of Na and Li atoms on metal surfaces. It is shown that the effective occupation dependent atom-surface coupling influences mainly the expectation values for producing positive, neutral, and negative particles for small work functions and high atom velocities. It is also shown that the temperature dependence of these expectation values is more visible, especially for magnetic solutions.
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