Uncertainty of DFT calculated mechanical and structural properties of solids due to incompatibility of pseudopotentials and exchange-correlation functionals

TL;DR

This paper investigates how the inconsistency between pseudopotentials and exchange-correlation functionals in DFT affects the accuracy of calculated mechanical and structural properties of solids, providing insights into error sources and functional performance.

Contribution

It systematically analyzes the errors introduced by pseudopotential and functional incompatibility in DFT calculations of solid properties and evaluates the performance of popular XC functionals.

Findings

Incompatibility causes significant errors in property predictions.

Pseudopotential choice impacts accuracy more than XC functional selection.

SCAN functional shows improved consistency over LDA and PBE.

Abstract

The demand for pseudopotentials constructed for a given exchange-correlation (XC) functional far exceeds the supply, necessitating the use of those commonly available. The number of XC functionals currently available is in the hundreds, if not thousands, and the majority of pseudopotentials have been generated for the LDA and PBE. The objective of this study is to identify the error in the determination of the mechanical and structural properties (lattice constant, cohesive energy, surface energy, elastic constants, and bulk modulus) of crystals calculated by DFT with such inconsistency. Additionally, the study aims to estimate the performance of popular XC functionals (LDA, PBE, PBEsol, and SCAN) for these calculations in a consistent manner.