AVS 52nd International Symposium
    Surface Science Friday Sessions
       Session SS2-FrM

Paper SS2-FrM6
Localized Electronic States Around a Single Kondo Impurity from a First Principles Embedding Theory

Friday, November 4, 2005, 10:00 am, Room 203

Session: Electronic Structure of Surfaces
Presenter: P. Huang, Princeton University
Authors: P. Huang, Princeton University
E.A. Carter, Princeton University
Correspondent: Click to Email
Scanning tunneling microscopy (STM) experiments of a single, magnetic adatom on non-magnetic metal surfaces reveal a sharp resonance in the immediate neighborhood around the adatom [e.g. Manoharan et al., Nature 403, 512 (2000)]. This intriguing observation has been interpreted as the presence of a "Kondo cloud", in which the localized d-electrons on the magnetic adatom hybridize with the metal band states to form an extended open-shell singlet near the Fermi level, thus effectively screening out the impurity moment. While the STM experiments have provided a first atomic-scale glimpse of this surface Kondo state, questions remain about the detailed electronic structure, and the nature of the low-lying excitations which give rise to the Kondo resonance width. We present a first-principles study of the electronic structure of a single Co adatom on Cu(111). Our approach is based on an embedding strategy [Kluner et al., PRL 86, 5954 (2001)], which views the Co adatom and nearest neighbor Cu atoms as a metal cluster embedded in a periodic slab background. The total Co/Cu(111) system is treated using density functional theory (DFT), which allows for a mean-field treatment of an extended periodic system. Using the DFT density for the total system, the effect of the background is cast into an effective embedding potential acting on the cluster. Explicitly-correlated theories (i.e. perturbation theory, configuration interaction) are subsequently applied to the embedded cluster in the presence of the embedding potential. The low-lying, many-body excited states are also treated within this same framework to yield excitation energies and wave functions.