Speaker: Rico Friedrich, Technische Universität Dresden

The accurate description of enthalpies of ionic materials is a critical enabler for the discovery and design of novel compounds such as two-dimensional systems and high-entropy ceramics. While standard density functional theory (DFT) can quantitatively describe the thermochemistry of intermetallic compounds, they fail to produce accurate results for ionic materials such as oxides. Formation enthalpies thus typically exhibit mean errors of several hundred meV compared to high-level thermochemical reference data [1].

To address this critical problem, we have developed the method of coordination corrected enthalpies (CCE). The correction is based on the chemical intuition that the number of bonds in a material determines its thermodynamic stability [1]. As such it is developed as a topological correction taking into account the cation-anion connectivity. In addition, CCE takes into account the cation oxidation state. The method substantially improves formation enthalpy predictions reducing mean absolute errors down to ~27 meV/atom for oxides, halides, and nitrides [1,2]. Moreover CCE is capable of correcting the relative stability of different polymorphs predicted with wrong energetic ordering from plain DFT – a distinct advantage compared to all earlier correction schemes. CCE has been implemented into the freely available AFLOW software suite for computational materials design offering automated structural analysis for coordination numbers, determination of oxidation states, and enthalpy correction based on only structural inputs [3]. It comes with command line functionality, a web interface, and a python environment. CCE is in particular an important enabler for the discovery of novel high-entropy ceramics which relies on accurate enthalpies between competing phases [4].

[1] R. Friedrich et al., npj Comput. Mater. 2019, 5, 59.
[2] R. Friedrich & S. Curtarolo, J. Chem. Phys. 2024, 160, 042501.
[3] R. Friedrich et al., Phys. Rev. Mater. 2021, 5, 043803.
[4] S. Divilov et al., Nature 2024, 625, 66 (2024).