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Phys. Rev. B 53 (1996) pp. 8052-8064
Embedding approach to the isolated adsorbate
Istituto Nazionale di Fisica della materia-Dipartimento di Fisica, Universita di Milano, Via Celoria 16, 20133 Milano, Italy
School of Physics, University of Bath, BA2 7AY, United Kingdom
Institute for Theoretical Physics, University of Nijmegen, Toernooiveld, NL-6525 ED Nijmegen, The Netherlands
Abstract
An embedding method is proposed, based upon Green function matching,
for calculating the electronic properties of an isolated adsorbate.
The self-consistent single-particle Schrodinger equation is solved
in a localized region containing the adsorbate and that part of the
substrate mainly perturbed by it.
The extended substrate is taken into account exactly
by an effective embedding potential.
The advantages of the method for the adsorption problem are discussed
and tested by a calculation of the electronic properties of isolated
Si and N adatoms on Al, modelled as jellium.
In the former case excellent agreement is found with the results
previously computed by other methods, in the latter, not previously
investigated by a first principles approach, the ionic-like character
of the bond is seen in the calculated charge densities and densities
of states.
Finally the problem of the lack of screening due to the presence of an
adatom on a simple metal surface is estimated by the generalized
phase shift theory.
This effect turns out to be an important contribution to the atom-surface
interaction energies, and it is corrected to first order by the use of
the grand-canonical energy functional.