G. R. Harp, X. Chen, Y. Ueda, M. D. Pauli, H. C. Poon, A. Wander, D. K. Saldin
We have developed a couple of novel methods for the simulation of photoelectron (PED) and Auger electron diffraction (AED) patterns.
The first was a full multiple-scattering cluster method , where the scattering atoms are arranged in a series of concentric spherical shells surrounding the photoemitting atom. Computer programs to implement these calculations are available from the CPC Program Library at Belfast, Northern Ireland. Descriptions of the three programs, PAD1 , PAD2 , and PAD3 of this suite have been published as three papers in the journal Computer Physics Communications.
Calculations of photoelectron diffraction patterns have been performed by this method for the surfaces of metals, metal alloys, metal oxides, hydrocarbon molecules on transition metal surfaces, and complex semiconductor surfaces.
Recently we have developed an alternative approach for full multiple-scattering calculations for AED and PED patterns, based on a path reversal formalism, and where the atoms are arranged in layers parallel to the surface, as in low energy electron diffraction (LEED). We believe this method is a significant improvement over previous methods for ordered surfaces, as it offers substantial increases in speed, without sacrificing accuracy.