Structure, Synthetic Pathway, and Properties of Metastable Phosphorus Carbide, PC.

Due to electronegativity (EN) differences, changing from CN to PC is not as trivial as simply replacing nitrogen by phosphorus in the CN structure. Hence, the nonexistent PC phase is nominally the higher-homologue analogue of the well-known CN, but its structure and properties are practically unknown for fundamental reasons. Here we predict, by means of an extensive structure search, three energetically favorable yet metastable PC phases adopting space groups 1̅, , and , followed by designing their synthetic routes.

Embedded Localized Molecular-Orbital Representations for Periodic Wave Functions.

To more straightforwardly provide local chemical-bonding reasoning in crystalline matter, we introduce a new approach to generate a real-space analogue of periodic electronic structures using "exact" top-down frozen-density embedding calculations. Based on the obtained real-space electronic structure, we then construct localized molecular orbitals and evidence that our technique compares favorably against the commonly used Wannier method, both in terms of numerical efficiency and details of chemical bonding. The new method has been implemented into the LOBSTER software package and designed as a black-box approach, digesting any periodic electronic structure from the currently supported codes, i.

Structural Transformation in LnHS (Ln = La, Nd, Gd, and Er) with Coordination Change between an S-Centered Octahedron and a Trigonal Prism.

Lanthanide hydride chalcogenides LnHSe and LnHTe (Ln = lanthanides) crystallize in two polymorphs, 2H and 1H structures (ZrBeSi-type and filled-WC-type structures, respectively), but the chemical origin of the structural selection is unknown. Here, we have expanded the LnHCh (Ch = O, Se, and Te) family to include LnHS (Ln = La, Nd, Gd, and Er) using high-pressure synthesis. LnHS adopts the 2H structure for large Ln (La, Nd, and Gd) and the 1H structure for small Er.

On the atomistic origin of the polymorphism and the dielectric physical properties of beryllium oxide.

Polymorphic beryllium oxide has been theoretically investigated from first principles as regards orbital occupancies, chemical bonding, polarization, as well as dielectric properties. By means of Crystal-Orbital Bond Index (COBI) analysis, the important role of the 2p orbitals on beryllium has been elucidated, in particular in terms of the correlation between polarization and beryllium-atom displacement, including the impact of the latter on the covalency of the BeO bond. In addition, several structural possibilities for a Be Mg O solid solution have been investigated for a Be content between 6% and 22%; for those, dynamically stable structures have been found, displaying large polarization values, more covalent BeO bonds, and a tendency for tetrahedral Be coordination.

Metal Hydride Vibrations: The Trans Effect of the Hydride.

-Dihydride complexes are important in many homogeneous catalytic processes. Here vibrational spectroscopy and density functional theory (DFT) methods are used for the first time to reveal that 4d and 5d metals transmit more effectively than the 3d metals influence of the ligand trans to the hydride and also couple the motions of the -hydrides more effectively. This property of the metal is linked to higher hydride reactivity.

Accurate embedding through potential reconstruction: A comparison of different strategies.

Potential reconstruction is a powerful strategy for deriving accurate (sometimes called "exact") embedding potentials in the context of density-dependent embedding methods. It is particularly useful for partitioning covalent bonds in such fragment-based electronic-structure methods. While the general approach is well defined and easily explained, there are a number of choices to be made in practice, concerning, e.

Serenity: A subsystem quantum chemistry program.

We present the new quantum chemistry program Serenity. It implements a wide variety of functionalities with a focus on subsystem methodology. The modular code structure in combination with publicly available external tools and particular design concepts ensures extensibility and robustness with a focus on the needs of a subsystem program.