Gradient correction scheme for bulk and defect positron states in materials: New developments

TL;DR

This paper reviews recent advancements in the generalized gradient approximation (GGA) for positron calculations, aiming to improve the accuracy of positron lifetime predictions in materials by incorporating new theoretical developments.

Contribution

It introduces new GGA approaches for positron calculations based on recent hypernetted-chain and quantum Monte Carlo results, enhancing lifetime estimations.

Findings

New GGA methods improve agreement with experimental positron lifetimes.

Incorporating recent theoretical data refines positron state calculations.

The developments potentially lead to more accurate defect characterization in materials.

Abstract

As local density approximation positron calculations systematically underestimate positron lifetimes when they are compared with their experimental counterparts, the generalized gradient approximation (GGA) for positrons was introduced in the 1990s, in analogy with the GGA for electrons. New developments in the GGA for positrons are summarized and presented here and it is also discussed how they affect and possibly improve calculated positron lifetimes. In particular, these new GGA approaches are based on the recent perturbed hypernetted-chain and quantum Monte Carlo results.