NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.
Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.
An official website of the United States government
Here’s how you know
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Multi-Pole Representation of the Dielectric Matrix
Published
Author(s)
J A. Soininen, J J. Rehr, Eric L. Shirley
Abstract
A good approximation for the electron self-energy or the electron quasiparticle properties is needed for an accurate calculation of x-ray absorption spectra. The GW approximation (GWA) has been found to be relatively reliable in predicting the quasiparticle energies and lifetimes in a large variety of systems. For solids, a part of a GWA calculation is the calculation of the inverse of the dielectric matrix epsilon^-1. We introduce an iterative method for calculating an accurate multi-pole approximation for epsilon^-1 and we apply it in GW calculations. Results for quasiparticle properties are presented for LiF and Si. For LiF we use these results to calculate the inelastic x-ray scattering spectra for energy loss close to the F K-edge. Other uses for this representations of epsilon^-1 will also be discussed.