A first-principles investigation of the linear thermal expansion coefficients of BeF: giant thermal expansion.

We present the results of a theoretical investigation of the linear thermal expansion coefficients (TECs) of BeF, within a direct Grüneisen formalism where symmetry-preserving deformations are employed. The required physical quantities such as the optimized crystal structures, elastic constants, mode Grüneisen parameters, and phonon density of states are calculated from first-principles. BeF shows an extensive polymorphism at low pressures, and the lowest energy phases [α-cristobalite with space group (SG) 422 and its similar phase with SG 422] are considered in addition to the experimentally observed α-quartz phase.

Introduction to flexible nanomaterials: microscopic mechanisms and macroscopic applications.

Yuan Cheng, Zibiao Li, Junfeng Gao, Hai-Dong Yu and Gang Zhang introduce this themed collection on flexible nanomaterials.

Coherent Spin and Quasiparticle Dynamics in Solution-Processed Layered 2D Lead Halide Perovskites.

Layered 2D halide perovskites with their alternating organic and inorganic atomic layers that form a self-assembled quantum well system are analogues of the purely inorganic 2D transition metal dichalcogenides. Within their periodic structures lie a hotbed of photophysical phenomena such as dielectric confinement effect, optical Stark effect, strong exciton-photon coupling, etc. Detailed understanding into the strong light-matter interactions in these hybrid organic-inorganic semiconductor systems remains modest.