Real Space Multiple Scattering Calculations of Relativistic Electron Energy Loss Spectra

TL;DR

This paper presents a first-principles method for calculating relativistic electron energy loss spectra using a real-space Green's function approach that includes relativistic effects, instrumental factors, and is applicable to aperiodic materials.

Contribution

It introduces a generalized real-space Green's function method that incorporates relativistic effects and instrumental factors for accurate REELS calculations in complex materials.

Findings

Successfully explains relativistic corrections to the magic angle in polarized EELS.

Demonstrates the method with an application to graphite C K edge.

Provides a versatile approach for aperiodic materials analysis.

Abstract

{\it Ab initio} calculations of relativistic electron energy loss spectra (REELS) are carried out using a generalization of the real-space Green's function code FEFF8 which is applicable to general aperiodic materials. Our approach incorporates relativistic effects in terms of the cross-section tensor within the dipole selection rule. In particular the approach explains relativistic corrections to the magic angle in polarized EELS experiments. Our generalization includes instrumental effects, such as the integral of the cross section over the impulse transfer dependence, to account for a finite detector aperture and electron beam width. The approach is illustrated with an application to the graphite C K edge.