Density functional theory and electronic structure

Abstract

We have tried to present a brief account of the activities in the realm of the DFT.Study of the band structure has aimed at the understanding of the single particle behaviour of a many body system. All the first principle self-consistent band structure methods are based on the foundations of the DFT.Therefore it is important to understand the physical meaning of the DFT bands via the Janak's theorem. In other words the band structure is an important practical aspect of the DFT.We have mentioned some of the successes and failures of it.

Out of the several current activities in the electron structure studies,an important problem has been to understand the systems without long range order,such as:liquids,amorphous solids and finite clusters. Out of several so-called ab-initio methods two major ones are currently used in such investigations. One is the LMTO method of Andersen,discussed elsewhere in this volume and the other one is the Car-Parrinello method,based on the molecular dynamical simulated annealing technique [37]. Both the methods utilise the LDA-DFT for constructing the effective potential.

Finally,we conclude that the electronic structure studies are very fundamental to the understanding of the properties of materials and for this the DFT has the requisite potential. We hope,the coming years will witness many more interesting developments in this active field of research.