First-Principles Study of a Positron Immersed in an Electron Gas

TL;DR

This study uses density functional theory to accurately model a positron in an electron gas, providing improved data on annihilation characteristics and revealing a significant high-momentum tail in the pair momentum density.

Contribution

It introduces a mean-field approach in the positron's reference frame for better electron-positron correlation modeling, aligning with advanced many-body results and highlighting new features in the momentum density.

Findings

Positron relaxation energies match advanced many-body calculations.

Annihilation rates are consistent with prior high-accuracy methods.

The pair momentum density exhibits a notable high-momentum tail.

Abstract

Calculations of the relaxation energy, contact pair-correlation function, and annihilating-pair momentum density for a single positron immersed in a homogeneous electron gas are presented. We achieve an accurate description of the electron-positron correlation effects by working in the reference frame in which the positron is stationary and using a mean-field approach based on single-component density functional theory. Our positron relaxation energies and annihilation rates are similar to those from the best existing many-body calculations. Our annihilating-pair momentum densities are significantly different from previous data, and include a "tail" beyond the Fermi edge.