Formation of phosphorus monoxide through the [Formula: see text] reaction

Phosphorus is a key and vital element for a diverse set of important biological molecules, being indispensable for life as we know. A deeper comprehension of its role in astrochemistry and atmospheric chemistry may aid in finding answers to how this element became available on Earth. The PO molecule is one of the main reservoirs of phosphorus in the interstellar medium (ISM), and a better understanding of the mechanisms and rate coefficients for its formation in the ISM is important for modelling its abundances. In this work, we perform multireference configuration interaction calculations on the formation of PO via the [Formula: see text] reaction, analyzing its potential energy surface and rate coefficients for the global reaction on both doublet and quartet states. We also perform DFT (M06-2X) and CCSD(T) calculations, in order to compare the results. We found that the OPO system possesses a high multiconfigurational character, making DFT and CCSD methodologies not suitable for its potential energy landscape calculation. The rate coefficients have been calculated using the master equation system solver (MESS) package, and the results compared to recent experimental data. It is shown that the quartet state contributes for temperatures higher than 700K. The computed rate coefficient can be described by a modified Arrhenius equation [[Formula: see text]] with [Formula: see text], [Formula: see text] and [Formula: see text] K.

Stability of neutral molecular polynitrogens: energy content and decomposition mechanisms

The potential application of all-nitrogen molecules as high energy density materials (HEDMs) has been attracting considerable scientific effort. If stable enough to be synthesized and stored, these systems may be used as a green source of energy. However, it is very difficult to obtain these structures under mild experimental conditions. Theoretical chemistry may aid in the search for polynitrogens that are more likely to have experimental usability. The barriers towards decomposition are an effective way to assess their stability, but these have not been thoroughly studied. Most of the previous effort in this direction focus on a single N_x case, each employing different accuracy levels, and the decomposition of caged structures has been little explored. Here we explore the stability and decomposition of several neutral molecular polynitrogens of different sizes and shapes using a common and accurate theoretical framework in order to compare among them, search for patterns and identify potential candidates for synthesis. We focus especially on new caged geometries, and our results indicate that the prismatic ones can be expected to present higher energy densities and be very stable with respect to unimolecular decomposition. It is shown that the energy content can be clearly stratified between chain, ring, cage and prismatic cage structures.

All-nitrogen molecules may provide green energy sources, releasing large amounts of energy without polluting byproducts. Here we predict the stability towards unimolecular decomposition of several structures and discuss their unusual chemistry.

An ab initio investigation of the adsorption properties of water on binary AlSi clusters

Nanoalloys represent potential catalysts for the water splitting reaction. The water–cluster interaction is a key aspect of the process, but is not fully understood. This work provides an in-depth study and insights into the AlxSiy·H₂O case.

Structural and homotop optimization of neutral Al–Si nanoclusters

The geometry and stability of aluminum–silicon alloys up to 13 atoms are investigated using electronic structure methods.