Pseudopotential study of binding properties of solids within generalized gradient approximations: The role of core-valence exchange-correlation

TL;DR

This paper investigates how the treatment of core-valence exchange-correlation interactions affects the accuracy of pseudopotential calculations in density-functional theory, especially comparing LDA and GGA approximations for solids.

Contribution

It highlights the differences in core-valence exchange-correlation treatment between LDA and GGA and their impact on binding property calculations in pseudopotential methods.

Findings

Pseudopotential linearization is similarly accurate and limited in GGA as in LDA.

Using LDA-derived pseudopotentials in GGA calculations leads to significant discrepancies.

Core-valence exchange-correlation behavior is a key factor in GGA-induced changes.

Abstract

In ab initio pseudopotential calculations within density-functional theory the nonlinear exchange-correlation interaction between valence and core electrons is often treated linearly through the pseudopotential. We discuss the accuracy and limitations of this approximation regarding a comparison of the local density approximation (LDA) and generalized gradient approximations (GGA), which we find to describe core-valence exchange-correlation markedly different. (1) Evaluating the binding properties of a number of typical solids we demonstrate that the pseudopotential approach and namely the linearization of core-valence exchange-correlation are both accurate and limited in the same way in GGA as in LDA. (2) Examining the practice to carry out GGA calculations using pseudopotentials derived within LDA we show that the ensuing results differ significantly from those obtained using pseudopotentials derived within GGA. As principal source of these differences we identify the distinct behavior of core-valence exchange-correlation in LDA and GGA which, accordingly, contributes substantially to the GGA induced changes of calculated binding properties.