Home Newsletter
News Books
Welcome to FreeScience.info Language/Lingua

Books 3054
· Book News
· Most clicked
· Least clicked

Search for a Book
Add a new Book

Electronic Excitations: Density-Functional VS Many-body Green\\\'s

Author: G. Onida, L. Reining, A. Rubio
Url: http://research.physics.illinois.edu/ElectronicStructure/598SCM-F04/Reining-ref-papers-for-lectures/Reining-RMP.pdf
Format: Pdf
Year: 2002
Category: TDDFT
Pages: 59
Clicks: 1138

Electronic excitations lie at the origin of most of the commonly measured spectra. However, the first-principles computation of excited states requires a larger effort than ground-state calculations, which can be very efficiently carried out within density-functional theory. On the other hand, two theoretical and computational tools have come to prominence for the description of electronic excitations. One of them, many-body perturbation theory, is based on a set of Green s-function equations, starting with a one-electron propagator and considering the electron-hole Green s function for the response. Key ingredients are the electron s self-energy S and the electron-hole interaction. A good approximation for S is obtained with Hedin s GW approach, using density-functional theory as a zero-order solution. First-principles GW calculations for real systems have been successfully carried out since the 1980s. Similarly, the electron-hole interaction is well described by the Bethe-Salpeter equation, via a functional derivative of S. An alternative approach to calculating electronic excitations is the time-dependent density-functional theory (TDDFT), which offers the important practical advantage of a dependence on density rather than on multivariable Green s functions. This approach leads to a screening equation similar to the Bethe-Salpeter one, but with a two-point, rather than a four-point, interaction kernel. At present, the simple adiabatic local-density approximation has given promising results for finite systems, but has significant deficiencies in the description of absorption spectra in solids, leading to wrong excitation energies, the absence of bound excitonic states, and appreciable distortions of the spectral line shapes. The search for improved TDDFT potentials and kernels is hence a subject of increasing interest. It can be addressed within the framework of many-body perturbation theory: in fact, both the Green s functions and the TDDFT approaches profit from mutual insight. This review compares the theoretical and practical aspects of the two approaches and their specific numerical implementations, and presents an overview of accomplishments and work in progress.

Similar Books
A guided tour of time-dependent density functional theory
Time-dependent Density Functional Theory
The Keldysh Formalism Applied to Time-Dependent Current-Density-Functional Theory
Density functional theory of time-dependent phenomena
Ten topical questions in time-dependent density functional theory
Excited states from time-dependent density functional theory
Time-dependent density-functional response theory for molecules
Time-dependent density-functional theory for extended systems
Real-Time Dynamics and Conical Intersections
Progress in Time-Dependent Density-Functional Theory
Time-Dependent Density Functional Theory
Introduction to TDDFT
A brief compendium of time-dependent density-functional theory

Home |  Authors | About | Contact Us |  Email 
 Copyright © 2002-2013 FreeScience.info. 

Best viewed with Mozilla 1.X 1024x768
free scientific books