Disordered enthalpy-entropy descriptor for high-entropy ceramics discovery.

The need for improved functionalities in extreme environments is fuelling interest in high-entropy ceramics. Except for the computational discovery of high-entropy carbides, performed with the entropy-forming-ability descriptor, most innovation has been slowly driven by experimental means. Hence, advancement in the field needs more theoretical contributions.

Settling the matter of the role of vibrations in the stability of high-entropy carbides.

High-entropy ceramics are attracting significant interest due to their exceptional chemical stability and physical properties. While configurational entropy descriptors have been successfully implemented to predict their formation and even to discover new materials, the contribution of vibrations to their stability has been contentious. This work unravels the issue by computationally integrating disorder parameterization, phonon modeling, and thermodynamic characterization.

Theoretical studies of the vibrational properties of octahedrane (CH): A polyhedral caged hydrocarbon molecule.

The vibrational properties of octahedrane (CH) are calculated using density-functional theory employing two different computational methods: an all-electron Gaussian orbital approach and a Naval Research Laboratory-tight-binding scheme (NRL-TB) coupled with molecular dynamics (NRL-TBMD). Both approaches yield vibrational densities of states for octahedrane that are in good general agreement with each other. NRL Molecular Orbital Library can also provide accurate infrared and Raman spectra which can be analyzed and compared with experimental results, while NRL-TBMD can be conveniently scaled up for larger finite-temperature simulations.

AFLOW-CHULL: Cloud-Oriented Platform for Autonomous Phase Stability Analysis.

A priori prediction of phase stability of materials is a challenging practice, requiring knowledge of all energetically competing structures at formation conditions. Large materials repositories-housing properties of both experimental and hypothetical compounds-offer a path to prediction through the construction of informatics-based, ab initio phase diagrams. However, limited access to relevant data and software infrastructure has rendered thermodynamic characterizations largely peripheral, despite their continued success in dictating synthesizability.

AFLOW-SYM: platform for the complete, automatic and self-consistent symmetry analysis of crystals.

Determination of the symmetry profile of structures is a persistent challenge in materials science. Results often vary amongst standard packages, hindering autonomous materials development by requiring continuous user attention and educated guesses. This article presents a robust procedure for evaluating the complete suite of symmetry properties, featuring various representations for the point, factor and space groups, site symmetries and Wyckoff positions.

Bright triplet excitons in caesium lead halide perovskites.

Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund's rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the 'dark exciton'.