文档介绍：Disordered Alloys and Their Surfaces:
The Coherent Potential Approximation
I. Turek1, J. Kudrnovsk´y2, and V. Drchal2
1 Institute of Physics of Materials, Academy of Sciences of the Czech Republic,
Ziˇˇ zkova 22, CZ-616 62 Brno, Czech Republic
2 Institute of Physics, Academy of Sciences of the Czech Republic,
Na Slovance 2, CZ-182 21 Praha 8, Czech Republic
Abstract. A recently developed ab initio approach to the electronic structure of sub-
stitutionally disordered alloys and their surfaces is reviewed. It is based on (i) the
tight-binding linear muffin-tin orbital (TB-LMTO) method in the atomic sphere appro-
ximation which provides a physically transparent solution of the one-electron problem
in metallic materials, (ii) the coherent potential approximation (CPA) for a mean-
field treatment of the substitutional randomness, and (iii) the surface Green functions
for a proper description of the true semi-infinite geometry of surfaces and interfa-
ces. Theoretical formulation of fundamental electronic quantities, both site-diagonal
(charge densities, densities of states) and site non-diagonal (the Bloch spectral fun-
ctions) is presented. Transformation properties of the LMTO-CPA theory as well as
specific problems of application of the local density approximation to random alloys
are briefly discussed and basic algorithms employed in the numerical implementation
of the formalism are described.
1 Introduction
Recent ab initio investigations of electronic properties of solids rely on the local
spin-density approximation (LSDA) to the density-functional formalism and on a
number of techniques solving the corresponding one-electron Schr¨odinger (Kohn-
Sham) eigenvalue problem. These prise, ., the Korringa-Kohn-
Rostoker (KKR) method [1,2], the linear muffin-tin orbital (LMTO) method
[3,4], the linear augmented plane-wave (LAPW) method [3,5], or the optimized
bination of atomic orbitals (LCAO) method [6]. They provide a rea