INVESTIGADORES
FABRICIUS Gabriel
artículos
Título:
Calculation of electronic and magnetic properties of transition-metal surfaces: Comparison of LMTO and tight-binding methods
Autor/es:
G. FABRICIUS; A.M. LLOIS; M. WEISSMANN; M.A. KHAN
Revista:
PHYSICAL REVIEW B
Editorial:
AMER PHYSICAL SOC
Referencias:
Lugar: New York; Año: 1994 vol. 49 p. 2121 - 2126
ISSN:
1098-0121
Resumen:
Low-dimensional systems have attracted a great deal of attention during
the past decade. The lowered symmetry and coordination number give rise
to new and interesting electronic and magnetic phenomena. Several ab initio
numerical methods have been developed to calculate the electronic and
magnetic structure of materials, but these calculations require a great
deal of computational effort. In order to study complex systems it is of
interest to be able to make use of simpler approximative methods. For
transition metals such an alternative approach is provided by the
tight-binding approximation. Within the conventional parametrized
tight-binding approach the lowered dimensionality of surfaces gives rise
to an unphysical filling of the surface d orbitals (sp-d
charge transfer), which in turn gives rise to lowered surface
magnetizations. Results obtained by applying the linear muffin-tin
orbital (LMTO) method to a repeated sequence of slabs and empty spheres
show the existence of a spillover coming from the s and essentially p surface orbitals, with the d-band
occupation remaining nearly the same as in the bulk materials. We
suggest in this work a simple way of parametrizing the tight-binding
Hamiltonian in such a way that the characteristics observed in LMTO
calculations are preserved and the simplicity of a tight-binding
approach remains valid. This is obtained by only adding a new layer of
orbitals on the surface in order to simulate the spillover. We compare
in this contribution results for Rh, Fe, and Cu (001) monolayers and
five-layer slabs obtained using LMTO and an unrestricted Hubbard
Hartree-Fock Hamiltonian with the surface parametrization.