A Multi-Atom, Self-Consistent, Relativistic Kkr Electronic Structure Program: Numerical Aspects and Applications
- PDF / 478,841 Bytes
- 7 Pages / 420.48 x 639 pts Page_size
- 45 Downloads / 126 Views
A MULTI-ATOM, SELF-CONSISTENT, RELATIVISTIC KKR ELECTRONIC STRUCTURE PROGRAM: NUMERICAL ASPECTS AND APPLICATIONS. G. Y. Guo and W. M. Temmerman, Daresbury Laboratory, Science and Engineering Research Council, Warrington WA4 4AD, UK ABSTRACT A KKR program for self-consistent electronic structure and total energy calculations of complex solids has been developed. This program has been used to study structural, electronic and magnetic properties of a number of solids. In this paper, we give a description of several numerical techniques used in this KKR program which might be of use to other practitioners. We also present some results obtained using this program: c/a ratio of hexagonal Y, elastic constants of Mo, TiC and MgO, and static spin susceptibility of Pd. INTRODUCTION The multiple scattering theory (MST) has appeared to be a powerful theoretical technique for studying the electronic properties of solids since its extension to the periodic muffin-tin (MT) potential was formulated by Korringa' and by Kohn and Rostokerl (thus known as the KKR method). The KKR method has many advantages. For example, it solves the periodic muffintin potential model exactly. The secular matrix may be separated into a term dependent only on the potential and a term only on the crystal structure. It has a fast convergence in angular momentum and thus, the effective dimension of the KKR secular matrix is small compared with that of other methods such as the augmented plane wave (APW) method. Furthermore, one can obtain the Green's function directly. This is important because all the observables may be calculated from the Green's function. Consequently, numerous KKR electronic structure calculations have been performed for metals 2 , metallic alloys3 and impurities in metals3 . The virtues of the KKR method and its early successes have stimulated further theoretical work to formulate a practical MST for the general crystalline potential. It turns out that the separability between structure and potential in the KKR MT method survives in the the full potential MST!. Our goal is to develop a fast full potential MST program for complex solids. However, we noticed that self-consistent (SC) KKR MT calculations for 'complex' solids were rare. Thus, as a first-step towards achieving this goal, we set up a SC KKR program for calculating electronic structures and total energies of complex solids two years ago. Evidently, due to the separability between structure and potential, this program can be straightfowardly extended to the full potentials by replacing the spherical scattering matrices with the full potential scattering matrices. Of course, calculating full potential scattering matrices is another formidable taskY In this paper we first give a brief description of our KKR program. We emphasize several numerical techniques which, we believe, will be useful to other practitioners. We then report selected results from several applications of this KKR program. ASPECTS OF KKR THEORY PROGRAM The central problem in SC KKR calculations is to solve e
Data Loading...
