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The computer program LOBSTER (Local Orbital Basis Suite Towards Electronic-Structure Reconstruction) enables chemical-bonding analysis based on periodic plane-wave (PAW) density-functional theory (DFT) output and is applicable to a wide range of first-principles simulations in solid-state and materials chemistry. LOBSTER incorporates analytic projection routines described previously in this very journal [J. Comput. Chem. 2013, 34, 2557] and offers improved functionality. It calculates, among others, atom-projected densities of states (pDOS), projected crystal orbital Hamilton population (pCOHP) curves, and the recently introduced bond-weighted distribution function (BWDF). The software is offered free-of-charge for non-commercial research. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Amorphous red phosphorus (a‐P) is one of the remaining puzzling cases in the structural chemistry of the elements. Here, we elucidate the structure, stability, and chemical bonding in a‐P from first principles, combining machine‐learning and density‐functional theory (DFT) methods. We show that a‐P structures exist with a range of energies slightly higher than those of phosphorus nanorods, to which they are closely related, and that the stability of a‐P is linked to the degree of structural relaxation and medium‐range order. We thus complete the stability range of phosphorus allotropes [Angew. Chem. Int. Ed. 2014, 53, 11629] by now including the previously poorly understood amorphous phase, and we quantify the covalent and van der Waals interactions in all main phases of phosphorus. We also study the electronic densities of states, including those of hydrogenated a‐P. Beyond the present study, our structural models are expected to enable wider‐ranging first‐principles investigations—for example, of a‐P‐based battery materials. [ABSTRACT FROM AUTHOR]

Despite its simple chemical constitution and unparalleled technological importance, the phase-change material germanium telluride (GeTe) still poses fundamental questions. In particular, the bonding mechanisms in amorphous GeTe have remained elusive to date, owing to the lack of suitable bond-analysis tools. Herein, we introduce a bonding indicator for amorphous structures, dubbed 'bond-weighted distribution function' (BWDF), and we apply this method to amorphous GeTe. The results underline a peculiar role of homopolar GeGe bonds, which locally stabilize tetrahedral fragments but not the global network. This atom-resolved (i.e., chemical) perspective has implications for the stability of amorphous 'zero bits' and thus for the technologically relevant resistance-drift phenomenon. [ABSTRACT FROM AUTHOR]

Quantum-chemical computations of solids benefit enormously from numerically efficient plane-wave (PW) basis sets, and together with the projector augmented-wave (PAW) method, the latter have risen to one of the predominant standards in computational solid-state sciences. Despite their advantages, plane waves lack local information, which makes the interpre-tation of local densities-of-states (DOS) difficult and precludes the direct use of atom-resolved chemical bonding indicators such as the crystal orbital overlap population (COOP) and the crystal orbital Hamilton population (COHP) techniques. Recently, a number of methods have been proposed to over-come this fundamental issue, built around the concept of basis-set projection onto a local auxiliary basis. In this work, we propose a novel computational technique toward this goal by transferring the PW/PAW wavefunctions to a properly cho- sen local basis using analytically derived expressions. In partic-ular, we describe a general approach to project both PW and PAW eigenstates onto given custom orbitals, which we then exemplify at the hand of contracted multiple-Ç Slater-type orbitals. The validity of the method presented here is illus-trated by applications to chemical textbook examples--dia-mond, gallium arsenide, the transition-metal titanium--as well as nanoscale allotropes of carbon: a nanotube and the C6o full-erene. Remarkably, the analytical approach not only recovers the total and projected electronic DOS with a high degree of confidence, but it also yields a realistic chemical-bonding pic-ture in the framework of the projected COHP method. [ABSTRACT FROM AUTHOR]

Phase‐change materials (PCMs) are an intriguing class of materials that enable non‐volatile data storage and other technological applications. To gain a thorough understanding of PCMs, a variety of advanced experimental techniques is routinely used, but theory and computer simulation have long been of central importance as well. In their Review @ RRL (article no. 1800579), Konze et al. describe the role that orbital‐based chemical‐bonding analyses have played in PCM research: they can be used to identify stabilizing ("bonding") and de‐stabilizing ("antibonding") interactions between atoms using local‐orbital basis sets or (nowadays) a projection from plane‐wave DFT output. Besides a concise overview of the methodology and a survey of applications to PCMs, Konze et al. also highlight recent applications in other materials classes, aiming to make new links to the PCM field—and so to enable new microscopic insight into the crystalline and amorphous structures of these important materials. [ABSTRACT FROM AUTHOR]

The atomic‐scale structures of chalcogenide phase‐change materials (PCMs) are directly relevant for macroscopic properties and practical applications. In PCMs and throughout materials science, quantum‐mechanically based atomistic simulations and chemical‐bonding analyses are increasingly helping to understand structures and properties of solids. Here, new insights into PCMs are highlighted that have recently been obtained from orbital‐based bonding indicators—in particular, from crystal orbital Hamilton population (COHP) analysis. Applications of these methods in other areas of solid‐state and materials chemistry are also discussed, from classical to emerging topics, which may have useful lessons for PCM research in store. It is hoped that this overview will inspire research in the field and enable new chemical insight into structures and properties of PCMs. The role of chemical‐bonding analyses for phase‐change materials research is highlighted in this Review. The focus is on energy‐resolved, orbital‐based bonding indicators: in particular, the crystal orbital Hamilton population (COHP) technique. This work surveys recent applications in the field and in neighboring areas, aiming to enable new chemical insight into the crystalline and amorphous structures of these important materials. [ABSTRACT FROM AUTHOR]