Automated Bonding Analysis with Crystal Orbital Hamilton Populations.

Invited for this month's cover are researchers from Bundesanstalt für Materialforschung und -prüfung (Federal Institute for Materials Research and Testing) in Germany, Friedrich Schiller University Jena, Université catholique de Louvain, University of Oregon, Science & Technology Facilities Council, RWTH Aachen University, Hoffmann Institute of Advanced Materials, and Dartmouth College. The cover picture shows a workflow for automatic bonding analysis with Python tools (green python). The bonding analysis itself is performed with the program LOBSTER (red lobster).

Automated Bonding Analysis with Crystal Orbital Hamilton Populations.

Understanding crystalline structures based on their chemical bonding is growing in importance. In this context, chemical bonding can be studied with the Crystal Orbital Hamilton Population (COHP), allowing for quantifying interatomic bond strength. Here we present a new set of tools to automate the calculation of COHP and analyze the results.

Synthesis, Crystal Structure, Symmetry Relationships, and Electronic Structure of Bismuth Carbodiimide Bi(NCN) and Its Ammonia Adduct Bi(NCN)·NH.

Bi(NCN), the first binary pnictogen carbodiimide, and its ammonia derivative Bi(NCN)·NH have been prepared via nonaqueous liquid-state low-temperature ammonolysis. The crystal structure of Bi(NCN)·NH in space group solved via single-crystal X-ray diffraction corresponds to a two-dimensional-like motif with layers of NCN alternating with honeycomb-like layers of edge-sharing distorted BiN octahedra, half of which are also coordinated by molecular ammonia occupying the octahedral holes. By contrast, Bi(NCN) adopts a higher-symmetric 2/ structure with a single Bi position and stronger distortion but empty octahedral voids.

Conduction Band Control of Oxyhalides with a Triple-Fluorite Layer for Visible Light Photocatalysis.

The discovery of building blocks offers new opportunities to develop and control properties of extended solids. Compounds with fluorite-type BiO blocks host various properties including lead-free ferroelectrics and photocatalysts. In this study, we show that triple-layered BiMO blocks (M = Bi, La, Y) in BiMOCl allow, unlike double-layered BiO blocks, to extensively control the conduction band.

Discovering Electron-Transfer-Driven Changes in Chemical Bonding in Lead Chalcogenides (PbX, where X = Te, Se, S, O).

Understanding the nature of chemical bonding in solids is crucial to comprehend the physical and chemical properties of a given compound. To explore changes in chemical bonding in lead chalcogenides (PbX, where X = Te, Se, S, O), a combination of property-, bond-breaking-, and quantum-mechanical bonding descriptors are applied. The outcome of the explorations reveals an electron-transfer-driven transition from metavalent bonding in PbX (X = Te, Se, S) to iono-covalent bonding in β-PbO.

LOBSTER: Local orbital projections, atomic charges, and chemical-bonding analysis from projector-augmented-wave-based density-functional theory.

We present an update on recently developed methodology and functionality in the computer program Local Orbital Basis Suite Toward Electronic-Structure Reconstruction (LOBSTER) for chemical-bonding analysis in periodic systems. LOBSTER is based on an analytic projection from projector-augmented wave (PAW) density-functional theory (DFT) computations (Maintz et al., J.

Achieving band convergence by tuning the bonding ionicity in n-type Mg Sb.

Identifying strategies for beneficial band engineering is crucial for the optimization of thermoelectric (TE) materials. In this study, we demonstrate the beneficial effects of ionic dopants on n-type Mg Sb . Using the band-resolved projected crystal orbital Hamilton population, the covalent characters of the bonding between Mg atoms at different sites are observed.

Cationic Pb Dumbbells Stabilized in the Highly Covalent Lead Nitridosilicate Pb Si N.

Due to the weak oxidative force of N , nitrides are only typically formed with the less electronegative metals. Meeting this challenge, we here present Pb Si N , the first nitridosilicate containing highly electron-affine cations of a metal from the right side of the Zintl border. By using advanced synchrotron X-ray diffraction, the crystal structure was determined from a tiny single crystal of 1×3×3 μm in size, revealing a significantly different bonding situation compared to all other nitridosilicates known so far.

First-Principles Chemical Bonding Study of Manganese Carbodiimide, MnNCN, As Compared to Manganese Oxide, MnO.

We have performed an in-depth study of the chemical bonding in manganese oxide (MnO) and carbodiimide (MnNCN) from correlated spin-polarized density functional calculations. The chemical-bonding data were produced using the LOBSTER package, which has recently been enabled to process PAW-based output from Quantum ESPRESSO. Our results show that the ground states of MnO and MnNCN are similar, namely, antiferromagnetic structures whose axes are the MnO cubic [111] and the MnNCN hexagonal [001] axes, in agreement with experimental results.

What is the Valence of Mn in Ga(1-x)Mn(x)N?

We investigate the current debate on the Mn valence in Ga(1-x)Mn(x)N, a diluted magnetic semiconductor (DMS) with a potentially high Curie temperature. From a first-principles Wannier-function analysis, we unambiguously find the Mn valence to be close to 2+ (d(5)), but in a mixed spin configuration with average magnetic moments of 4μ(B). By integrating out high-energy degrees of freedom differently, we further derive for the first time from first-principles two low-energy pictures that reflect the intrinsic dual nature of the doped holes in the DMS: (1) an effective d(4) picture ideal for local physics, and (2) an effective d(5) picture suitable for extended properties.