Disorder, short-range order, and defect interactions in thermodynamic modeling from first-principles

Real materials are rarely ideal, perfectly ordered crystals. Instead, materials properties, behavior, and functionality are usually influenced, if not determined, by defects, doping, and disorder. Moreover, these non-idealities often do not observe the completely random atomic distributions that underpin simple thermodynamic models. Instead, short-range order can often cause significant contributions to both enthalpy and entropy, creating both challenges and opportunities for modeling based on first-principles total energy calculations. This presentation will review recent works that approach this issue from different angles and attempt to integrate the different perspectives into a coherent picture, including: [1] Atomic site disorder in non-equilibrium synthesis of ZnGeN₂, modeled by cluster-expansion Monte-Carlo (MC) simulations. [2] Heterostructural phase diagram of (Cd,Zn)₃As₂ topological semimetals, where short range order effects are accounted for by thermodynamic integration of first-principles MC with model functions. [3] Predicting the reduction behavior of highly off-stoichiometric (Sr,Ce)MnO_3-δ perovskites via free energy contributions due to defect interactions.