Coordination corrected ab initio formation enthalpies

Rico Friedrich,Marco Buongiorno Nardelli,Cormac Toher,Demet Usanmaz,Marco Fornari,Andrew Supka,Corey Oses,Stefano Curtarolo

doi:10.1038/s41524-019-0192-1

Abstract

The correct calculation of formation enthalpy is one of the enablers of ab-initio computational materials design. For several classes of systems (e.g. oxides) standard density functional theory produces incorrect values. Here we propose the “coordination corrected enthalpies” method (CCE), based on the number of nearest neighbor cation–anion bonds, and also capable of correcting relative stability of polymorphs. CCE uses calculations employing the Perdew, Burke and Ernzerhof (PBE), local density approximation (LDA) and strongly constrained and appropriately normed (SCAN) exchange correlation functionals, in conjunction with a quasiharmonic Debye model to treat zero-point vibrational and thermal effects. The benchmark, performed on binary and ternary oxides (halides), shows very accurate room temperature results for all functionals, with the smallest mean absolute error of 27(24) meV/atom obtained with SCAN. The zero-point vibrational and thermal contributions to the formation enthalpies are small and with different signs—largely canceling each other.

Highlights

The accurate prediction of the thermodynamic stability of a compound—crucial in computational materials design1—mostly relies on the calculation of the formation enthalpy: the enthalpy change with respect to elemental reference phases
Where U0A;DxF1T1⁄4 Oxn, Ui0;density functional theory (DFT), and UO0;2DFT are the total energies of the compound per formula unit, the i-element reference phase per atom, and O2, respectively, and x1, ..., xn are stoichiometries
We have introduced a coordination corrected enthalpies (CCE) scheme based on the number of nearest-neighbor cation–anion bonds. 71(7) ternary oxides are used as a test set

Summary

Introduction

The accurate prediction of the thermodynamic stability of a compound—crucial in computational materials design1—mostly relies on the calculation of the formation enthalpy: the enthalpy change with respect to elemental reference phases. For systems where elements and compounds are metallic, i.e. chemically similar, accurate results are usually obtained by using standard (semi)local approximations to DFT.[2,3] They include the local density approximation (LDA)[4,5] or the generalized gradient approximation (GGA), for instance PBE.[6] In this way, formation energies for millions of metal alloys have already been calculated in materials databases such as AFLOW,[7,8,9,10] the Materials Project,[11,12] and OQMD.[13,14]. For reaction energies between binary and ternary oxides, within a similar chemical realm, a smaller average error of about 24–35 meV/atom has been observed.[19]

Methods

Results

Conclusion