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The multiconfigurational dynamical symmetry (MUSY) connects the shell, collective, and cluster models of atomic nuclei for the case of multi-shell excitations. Therefore, it can give a unified description of various phenomena. The shape isomers are obtained from the investigation of the stability and consistency of the symmetry, and selection rules connect them to the possible cluster configurations and the related reaction channels. A simple, dynamically symmetric Hamiltonian turns out to be able to provide a unified description of the gross features of spectra of different regions of excitation energy and deformation. Some predictions of MUSY have been justified by experimental observations. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2), a stable gaseous species, occupies the troposphere layer of the atmosphere. Following it, the environment gets warmer, and the ecosystem changes as a consequence of disrupting the natural order of our life. Due to this, in the present reasearch, the possibility of carbon fixation of CO2 by using borane was investigated. To conduct this, each of the probable reaction channels between borane and CO2 was investigated to find the fate of this species. The results indicate that among all the channels, the least energetic path for the reaction is reactant complex (RC) to TS (A-1) to Int (A-1) to TS (A-D) to formic acid (and further meta boric acid production from the transformation of boric acid). It shows that use of gaseous borane might lead to controlling these dangerous greenhouse gases which are threatening the present form of life on Earth, our beautiful, fragile home.

The multiconfigurational dynamical symmetry (MUSY) connects the shell, collective, and cluster models of atomic nuclei for the case of multi-shell excitations. Therefore, it can give a unified description of various phenomena. The shape isomers are obtained from the investigation of the stability and consistency of the symmetry, and selection rules connect them to the possible cluster configurations and the related reaction channels. A simple, dynamically symmetric Hamiltonian turns out to be able to provide a unified description of the gross features of spectra of different regions of excitation energy and deformation. Some predictions of MUSY have been justified by experimental observations.

< p>Oxidation of fullerenes, carbon nanotubes, and graphene, is one of the first proposed and successful approaches for further functionalization of these nano dimension carbon allotropes. Also, the C20 fullerene, as the smallest known carbon cage, is one of the most important species, in the future of nanotechnology. In this regard, the potential energy surface (PES) study suggests that reaction between nitric (V) acid and C20 fullerene, first leads to the production of a relatively meta-stable kinetically allowed intermediate via a [2+3] cycloaddition. After the intermediate is produced, it would subsequently be decomposed to a C20O open-shell fullerene and a HNO2molecule. Such oxidations were observed via the reaction between strong acids and some of the nano-sized carbon allotropes like carbon nanotube CNTs or spherical fullerenes. The results showed that the produced intermediate directly changes to the final product of oxidation, in a fast process.

Developing novel electrocatalysts with desirable activity and stability is always full of challenge in electrochemical energy conversion. Here, specific carbon shell encapsulated Au (Au@C) nanoparticles are prepared by a laser ablation in liquids method and used as the oxygen reduction reaction (ORR) electrocatalysts. Such Au@C nanoparticles exhibit excellent catalytic activity toward ORR with an onset potential of 0.98 V and a half-wave potential of 0.87 V, better than that of commercial Pt/C. More importantly, the Au@C catalyst exhibits unrivalled stability for 3000 CV cycles for ORR in 0.1 M KOH, dramatically superior to Pt/C and pure Au catalysts. The density functional theory (DFT) calculations and SCN− ions to poison metal-based active sites are conducted to Au@C catalyst, and the results indicate that the structural defects of carbon shells supply an access for the reactants to contact the core Au nanoparticles, causing the catalytic reaction, meanwhile the carbon shells prevent the degeneration of core Au nanoparticles in the harsh electrolytes enhancing the durability of Au effectively. [ABSTRACT FROM AUTHOR]

We have examined here the possibility of functionalization of the B12N12 cluster by methyl azide by means of a [2 + 3] cycloaddition reaction in analogy with the spontaneous functionalization of C20 fullerene using the same reaction. To achieve more reliable data, all possible interactions at different positions and orientations were considered by reaction channel study and potential energy surface calculations. Also, Born–Oppenheimer molecular dynamics simulations were used to find probable species which could emerge during the reactions. [ABSTRACT FROM AUTHOR]

The dissociative excitation of the odd triplet levels of a nickel atom by the collisions of electrons with nickel dibromide molecules is investigated using extended crossing beams and recording the optical signal of the excited atoms. In all, 50 excitation cross-sections of Ni I spectral lines are measured at an electron energy of 100 eV. Nine optical excitation functions (OEFs) are recorded in a range of electron energies of 0–100 eV. The obtained data on the dissociative excitation cross-sections of the spectral lines are used for the calculation of the excitation cross-sections of the energy levels as well as the contribution from the cascade transitions. The possible channels of dissociative excitation which manifest themselves in the region of low electron energies (E < 22 eV) are discussed. [ABSTRACT FROM AUTHOR]

Night-time gas-phase reaction of CH 3 OCH 2 CH 2 Cl initiated by NO 3 radical has been carried out using dual-level of quantum methods. Optimization and frequency calculations are performed at hybrid density functional M06-2X/6-31+G(d,p) level of theory and energy calculations are further refined at CCSD(T)/6-311++G(d,p) level of theory. All the stationary points (both minima and saddle points) have been located and characterized on the potential energy surfaces. The result shows that H-atom abstraction from the OCH 2 site of CH 3 OCH 2 CH 2 Cl initiated by NO 3 radical is thermodynamically and kinetically more favorable reaction pathways than other reaction channels. The atmospheric lifetime, radiative efficiency and global warming potentials (GWPs) have also been reported in this work. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2 ), a stable gaseous species, occupies the troposphere layer of the atmosphere. Following it, the environment gets warmer, and the ecosystem changes as a consequence of disrupting the natural order of our life. Due to this, in the present reasearch, the possibility of carbon fixation of CO 2 by using borane was investigated. To conduct this, each of the probable reaction channels between borane and CO 2 was investigated to find the fate of this species. The results indicate that among all the channels, the least energetic path for the reaction is reactant complex (RC) to TS (A-1) to Int (A-1) to TS (A-D) to formic acid (and further meta boric acid production from the transformation of boric acid). It shows that use of gaseous borane might lead to controlling these dangerous greenhouse gases which are threatening the present form of life on Earth, our beautiful, fragile home., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Mohammadi, Siadati, Ahmadi, Habibzadeh, Poor Heravi, Hossaini and Vessally.)

Two different hydrolysis mechanisms of metabolic product from tirapazamine's enzymatic catalysis have been studied by density functional theory (DFT) at the B3LYP/6-31G(d) and B3LYP/6-311+G(d) levels. The results indicate that the activation barrier of rate-controling step of Brown's model is smaller than that of Denny's model. [ABSTRACT FROM AUTHOR]

The understanding of the photochemistry of antibiotic compounds is important because it gives the direct information on the possible environmental pollution caused by them. Due to their large size, the theoretical studies of their excited-state reactions are rather challenging. In current work, we combined the on-the-fly trajectory surface-hopping dynamics, conical-intersection optimizations and excited-state pathway calculations to study the photochemistry of the trans -isomer of nitrofurantoin, a widely-used drug to treat the urinary tract infections. The dynamics-then-pathway approach was taken. First the trajectory surface hopping dynamics at the state-averaged complete-active-space self-consistent-field (SA-CASSCF) level with small active space and small basis sets were run. Second, the minimum-energy conical-intersection optimizations were performed. Finally the excited pathways from the Frank-Condon region to different reaction channels were built at the multi-state multi-reference second-order perturbation (MS-CASPT2) level with large active space and large basis set. Several possible channels responsible for the photo-induced reaction mechanism of the trans -nitrofurantoin were obtained, including the cleavage of the NO bond of the NO 2 moiety, the photoisomerization at the central CN bond, and other internal conversion channels. Our findings give some preliminary explanations on available experimental observations. It is also demonstrates that the current theoretical approach is a powerful tool to explore the excited-state reactions in the photochemistry of media-sized or large-sized drug compounds. • Photochemistry of nitrofurantoin is studied by ab initio and dynamics calculations. • Photo-reactions are governed by isomerization, O-atom detachment and –NO 2 motion. • Photoisomerization channel is predicted, consistent with experimental works. • The O-atom generation channel results in the degenerated ground states. • Pollutant photoreactions can be predicted by theoretical chemistry. [ABSTRACT FROM AUTHOR]