Distinguishing Thermal Fluctuations from Polaron Formation in Halide Perovskites.

Recent angle-resolved photoelectron spectroscopy (ARPES) measurements of the hole effective mass in CsPbBr_{3} revealed an enhancement of ∼50% compared to the bare mass computed from first principles for CsPbBr_{3} at T=0  K. This large enhancement was interpreted as evidence of polaron formation. Employing accurate finite-temperature first-principles calculations, we show that the calculated hole effective mass of CsPbBr_{3} at T=300  K can explain experimental results without invoking polarons.

LoreX: A Low-Energy Region Explorer Boosts Efficient Crystal Structure Prediction.

Machine learning has boosted the remarkable development of crystal structure prediction (CSP), greatly accelerating modern materials design. However, slow location of the low-energy regions on the potential energy surface (PES) is still a key bottleneck for the overall search efficiency. Here, we develop a low-energy region explorer (LoreX) to rapidly locate low-energy regions on the PES.

Nature of Disordering in γ-Ga_{2}O_{3}.

Polymorphs commonly exist for various materials, enabling phase engineering for diverse material properties. While the crystal structures of different polymorphs can, in principle, be experimentally characterized, interpreting and understanding complex crystal structures can be very challenging. Using Ga_{2}O_{3} as a prototype, here we show that the crystal structure of γ-Ga_{2}O_{3} has long been misinterpreted from either theory or experiment.

Critical Role of Configurational Disorder in Stabilizing Chemically Unfavorable Coordination in Complex Compounds.

The crystal structure of a material is essentially determined by the nature of its chemical bonding. Consequently, the atomic coordination intimately correlates with the degree of ionicity or covalency of the material. Based on this principle, materials with similar chemical compositions can be successfully categorized into different coordination groups.

Computational Screening of Promising Deep-Ultraviolet Light Emitters.

Deep-ultraviolet (DUV) light sources are technologically highly important, but DUV light-emitting materials are extremely rare; AlN and its alloys are the only materials known so far, significantly limiting the chemical and structural spaces for materials design. Here, we perform a high-throughput computational search for DUV light emitters based on a set of carefully designed screening criteria relating to the sophisticated electronic structure. In this way, we successfully identify 5 promising material candidates that exhibit comparable or higher radiative recombination coefficients than AlN, including BeGeN, MgNF, KCaBr, KHS, and RbHS.