Dynamic image potential at an Al(111) surface

TL;DR

This paper calculates the electronic self-energy at an Al(111) surface using the GW method, revealing the nature of the image potential and its dependence on correlation effects, with implications for surface electronic properties.

Contribution

It introduces a GW-based approach to evaluate the image potential at a metal surface, highlighting the role of correlation in unoccupied states and the inward shift of the image-plane.

Findings

The image potential for unoccupied states arises from correlation effects.

The effective image-plane is closer to the surface than classical predictions.

Atomic structure influences the position of the image-plane.

Abstract

We evaluate the electronic self-energy Sigma(E) at an Al(111) surface using the GW space-time method. This self-energy automatically includes the image potential V_{im} not present in any local-density approximation for exchange and correlation. We solve the energy-dependent quasiparticle equations to obtain surface state wavefunctions, and calculate the effective local potential experienced by electrons in the near-surface region. We find that V_{im} for unoccupied states is due to correlation (not exchange). The image-plane position for interacting electrons is considerably closer to the surface than for the purely electrostatic effects felt by test charges, and, like its classical counterpart, is drawn inwards by the effects of atomic structure.