Department of Theoretical Physics, University of Lund, S-223 62 Lund,
Sweden;
Max-Planck-Institut für Festkörperforschung, Stuttgart,
Germany
Calculations of ground-state and excited-state properties of materials have been one of the major goals of condensed matter physics. Ground-state properties of solids have been extensively investigated for several decades within the standard density functional theory. Excited-state properties, on the other hand, were relatively unexplored in ab initio calculations until a decade ago. The most suitable approach up to now for studying excited-state properties of extended systems is the Green function method. To calculate the Green function one requires the self-energy operator which is non-local and energy dependent. In this article we describe the GW approximation which has turned out to be a fruitful approximation to the self-energy. The Green function theory, numerical methods for carrying out the self-energy calculations, simplified schemes, and applications to various systems are described. Self-consistency issue and new developments beyond the GW approximation are also discussed as well as the success and shortcomings of the GW approximation.
A reprint of this paper can be obtained at the cond-mat in Germany
or in the US
.
Reports on Progress in Physics, 61 237-312, 1998.
Max-Planck Institut für Festkörperforschung;
Postfach 80 06 65 D-70506 Stuttgart
