Ab initio simulation of photoemission spectroscopy in solids: Plane-wave pseudopotential approach, with applications to normal-emission spectra of Cu(001) and Cu(111)

TL;DR

This paper presents a novel ab initio method for simulating photoemission spectra in solids, explicitly including transmission and matrix-element effects, and applies it to copper surfaces with improved accuracy.

Contribution

The authors develop a new plane-wave pseudopotential approach within density-functional theory that explicitly accounts for transmission and matrix-element effects in photoemission simulations.

Findings

Spectra for Cu(001) and Cu(111) agree with experiments and previous theories.

Including surface optics corrections improves spectral accuracy.

LDA+U method enhances correlation effect modeling.

Abstract

We introduce a new method for simulating photoemission spectra from bulk crystals in the ultra-violet energy range, within a three-step model. Our method explicitly accounts for transmission and matrix-element effects, as calculated from state-of-the-art plane-wave pseudopotential techniques within density-functional theory. Transmission effects, in particular, are included by extending to the present problem a technique previously employed with success to deal with ballistic conductance in metal nanowires. The spectra calculated for normal emission in Cu(001) and Cu(111) are in fair agreement with previous theoretical results and with experiments, including a newly determined spectrum. The residual discrepancies between our results and the latter are mainly due to the well-known deficiencies of density-functional theory in accounting for correlation effects in quasi-particle spectra. A significant improvement is obtained by the LDA+U method. Further improvements are obtained by including surface-optics corrections, as described by Snell's law and Fresnel's equations.