International Journal of Quantum Chemistry最新文献

In the present study, a novel strategy for constructing new cage energetic compounds with both high energy and low sensitivity was proposed. That is to use a 3D nitrogen-rich cage compound as the core parent molecule to set the basis for obtaining high energy, followed by the introduction of a moderate number of nitro groups into the cage, which are linked with the carbon atoms to further improve the energy without increasing the sensitivity obviously and controlling the reaction difficulty caused by too many nitro groups as low as possible. The amino groups were introduced into the structure also to adjust the balance of energy and sensitivity. Finally, more importantly, the formation of nitrogen-rich cage and the introduction of nitro/amino groups were achieved synchronously by a typical and attractive one-step reaction (The Diels–Alder reaction) which possesses 100% atomic efficiency. Based on this strategy, six series of amino-substituted nitrogen-rich azoles were used as the dienes to react with different dienophiles like tetranitroethylene (TNE) to form the final cage products. From the theoretical investigation results, five optimal compounds (PA0, PB0, PC0, PE0, PE1) with low reaction energy barrier (11.2–31.6 kcal/mol) may set the high energy of CL-20 and low sensitivity of TNT together, and have been screened out as new advanced energetic compounds successfully. This study may provide a new feasible strategy and a unique perspective for developing new advanced energetic compounds.

The stability of a model two-electron system with tunable interelectronic repulsion has been explored with respect to a scaling parameter $��\kappa �$. The complex scaling method within an orbital-based configuration expansion and the Ritz variational method with an explicitly correlated Hylleraas-type basis set are considered for this purpose. An estimation of critical scaling parameter $��{�\kappa �}_{�c�}�$, at which the bound state transforms into a shape resonance state, is reported. The position and width of the quasibound state for $��\kappa �>�{�\kappa �}_{�c�}�$ are calculated by adopting the complex scaling method. The onset of quantum phase transition in the vicinity of $��{�\kappa �}_{�c�}�$ is discussed through the estimation of geometrical properties such as radial moments.

Wogonin and wogonoside are derived from the traditional Chinese medicine Scutellaria baicalensis. Due to their various biological activities, the research on their various properties has simulated great interest. In this work, we systematically and theoretically studied the intra- and inter- interactions of wogonin and wogonoside. For intra- interactions, their details were exhibited with the help of IRI, BO, and LOL-π. To predict inter-interactions, the results of ESP, van der Waals potential, and hydrogen and hydrophobic interactions were shown. Our meaningful research results will provide theoretical guidance for more efficient utilization of wogonin and wogonoside for corresponding studies, and will help confirm the structure–activity relationship, an essential topic nowadays, of these two molecules.

Reaction free energies of hydrogen peroxide (H₂O₂) and hydrated transition metal ions to form hydroxyl radical, which is known as Fenton or Fenton-like reactions, are calculated by DFT methods. Standard electrode potentials of M²⁺/M³⁺ (M = Ti, V, Cr, Mn, Fe, Co) in aqueous solutions are calculated as benchmarks for the selected hybrid functionals and the basis sets. Mean absolute errors of the calculated redox potentials are comparable to those of the previous DLPNO-CCSD(T) calculation in most of the combinations. In contrast, calculated Gibbs free energies of hydroxyl radical formation are dependent on the choice of the functionals, and PBE0 gives the best results. The effect of anion substitution in the first hydration shell and Fenton-like reactions of other metal ions (Ti³⁺, V²⁺, Cr²⁺, Mn²⁺) are also examined.

LaTaON₂ is a promising visible-light-responsive photocatalyst for water splitting because of its broad visible light absorption and suitable band edge positions. However, the high defect concentration hinders the charge transfer and results in the poor photocatalytic performance of LaTaON₂. Loading proper cocatalysts is one of the most efficient strategies for promoting charge separation/transfer and achieving high reaction activity. In this work, we have used density functional theory calculations to study the depositions of Pt, Ru, and Ni single atom cocatalysts on LaTaON₂(010) surface. The most stable adsorption configuration is the same site for all the elements, namely the top of the N atom on the La-terminated surface and the fourfold hollow site on the Ta-terminated surface. The adsorption of the metal single atom on Ta-termination is stronger than that on La-termination due to the formation of more bonds. Upon the deposition, no localized impurity states appear in the middle of the forbidden gap since the nd states of metal adatoms are located within the valence band and conduction band of LaTaON₂. The efficiency of the photocatalysts is probed by investigating their ability to adsorb the H atom in a thermodynamically favorable manner. Our results reveal that the energetically favorable sites of HER are the N atom on the La-termination and the O and N atoms on the Ta-termination, respectively. Compared with the clean surface, the surfaces with Pt, Ru, and Ni single adatoms exhibit higher performance for HER because loading metal cocatalysts can further activate the surface nonmetal atoms and reduce the Gibbs free energy of hydrogen adsorption. The work gives an atom-level insight into the role of metal single atom cocatalysts in the LaTaON₂ photocatalyst for hydrogen production.

This manuscript introduces a relativistic method to determine the electronic structure and electron collision ionization process of atoms placed in a semiclassical plasma. The method uses the effective interaction pseudo-potential derived for general two interacting charged particles taking into account the quantum mechanical and screening effects to model the plasma environment. The Dirac equation with the aforementioned pseudo-potential is solved numerically to obtain the bound state and continuous state wave functions. The method starts from the Dirac equation and thus includes the relativistic effects on the one-electron level. The effects coming from the Breit interaction and quantum electrodynamics corrections are included. As a representative example, we investigate the plasma electron screening effect and the plasma ion screening effect, separated and combined, on the level delocalization and electron collision ionization process of hydrogen atoms placed in a strongly coupled semiclassical plasma environment. Properties of the spectra such as energies, oscillator strengths, and relativistic energy shifts corresponding to bound states are determined. The relativistic distorted wave method is used to provide a consistent and elaborate description of the ionization cross sections of the electron collisions involved. Our results reveal that the plasma electron shielding effect contributes to a reduced ionization potential and oscillator strength, while increasing the electron impact ionization cross section, when compared with the results of an isolated scenario. When the plasma ion shielding effect is included, these observed alterations are further enhanced, highlighting the considerable role of the plasma ion shielding effect in this process. Our results are in agreement with other theoretical data. The present study not only extends the relativistic distorted wave approach to the analysis of collision processes in semiclassical plasmas and evaluates the impact of the plasma ion screening effect but also has practical implications for radiation physics, inertial confinement devices, and the interiors of stars.

This research work focuses on the theoretical investigation and evaluation of the biological activities of three medicinal plants: black cumin and Artemisia, which have been widely used in the treatment of coronavirus, and Euphorbia Atlantica Coss, belonging to the Euphorbiaceous family. The molecules that are the subject of our work are: thymol, thymoquinone, thujone, and artemisinin, as well as methyl galat (M1) and pholoroacetophenone 4-O-B-D-glucopyranoside (M2); molecules extracted from the plant Euphorbia Atlantica Coss. Structural and orbital studies are carried out on these species, with the aim of establishing a structure-biological activity relationship. The obtained results an energy gap of the order of ~5.5 eV is found for most of the molecules. Potential electrostatic calculations show that Thymol, M1, and M2 are susceptible to electrophilic attack. Thymol has a high polarizability and therefore a good activity, while a good electronic transfer is observed for thujone and artemisinin. Our study showed that black cumin has much more intense absorbance peaks than other plants. AIM analysis identifies critical points at CO and OH bonds, with strong hydrogen bonding in artemisinin. Molecular docking shows promising inhibitory potential of artemisinin. Assessment of the main ADME properties showed that all compounds except M1 and M2 comply with Lipinski's rule, which predicts good oral bioavailability.

The study investigated the contribution of hydroxymethanesulfonic acid (HMSA) to the formation of new particles in the presence of atmospheric bases such as ammonia (A), methylamine (MA), dimethylamine (DMA) and water (W) by DLPNO-CCSD(T)/aug-cc-pVTZ//B3LYP-D3/aug-cc-pVTZ(aug-cc-pV(T+d)Z for sulfur) level. Clusters containing HMSA were found easily to form six− or eight−membered ring structures via SO—H⋯O (HMSA donor), O—H⋯O/N (W donor), N—H⋯O/N (A/MA/DMA donor), and C—H⋯O (MA/DMA donor) hydrogen bonds. Due to the synergistic interaction between X and Y molecules, the stability of HMSA−X−Y trimers is thermodynamically more favorable than HMSA−X dimers, and proton transfer was found to be exothermic and barrier−free in HMSA−X−Y trimers. Moreover, the stability of HMSA−X−Y trimers increased with higher alkalinity of X and Y, leading to decreased evaporation rates. The study highlights the significance of HMSA−containing trimers in nucleation processes for new particle formation, suggesting their potential role as nucleation centers in atmospheric conditions.

Molecular descriptors are essential tools for analyzing the structural and physicochemical properties of molecular systems. In this study, novel modified reverse degree-sum descriptors are applied to analyze kekulenes, a distinctive class of cycloarenes known for their aromaticity, superaromaticity, and exceptional electronic properties. These descriptors are further integrated with graph entropy measures to evaluate the structural complexity and energetic properties of three kekulene tessellation patterns: Zigzag, armchair, and rectangular. Energetic parameters, including total $��\pi �$-electron energy, HOMO-LUMO energy gaps, and resonance energy, are computed to provide a detailed understanding of the kinetic and thermodynamic stability of these tessellations. The modified reverse degree-sum-based methodology applies to all degree-sum-based descriptors. The variable parameter ‘$��k�$’ adjusts the molecular graph's degree-sum sequence to best fit the unique properties of each dataset. These enhancements strengthen correlations with physicochemical properties, improving the descriptor's effectiveness in structural analysis. Furthermore, regression models are developed to predict the energetic behavior of high-dimensional kekulene structures, offering a robust framework for advanced studies in molecular stability and design.

Sugar, as a denitration agent, has broad application prospects in the field of high-level radioactive liquid waste (HLLW) treatment. Understanding the interaction mechanism between nitric acid and sugar is crucial for the development of HLLW treatment. This study presents a detailed reaction mechanism, revealing key intermediates (HNO₂) and pathways (generation of carboxyl groups) leading to critical products (NO₂, NO, CO₂, and CO). The work shows five different paths leading to the ring-opening of β-D-glucopyranose. The results indicate that the ring-opening path involving the interaction of H₃O⁺ with glycosidic oxygen has the greatest kinetic advantage, with lower energy of highest point (EHP) (63.6 kJ/mol) and lower highest energy barrier (HEB) (49.2 kJ/mol). Furthermore, carbon oxides, as key gaseous products, exhibit a synergistic relationship with the generation pathways of nitrogen oxides, promoting each other. In addition, through thermodynamic analysis of the four reaction products (NO₂, NO, CO₂, and CO), the study shows that the reactions producing NO₂ and NO are spontaneous exothermic reactions, while the reactions generating CO₂ and CO are non-spontaneous endothermic reactions. The study aims to elucidate the atomic-scale interaction mechanism between sugar-based denitration agents and nitric acid, providing a theoretical basis for the application of natural polysaccharides in HLLW, while also opening new avenues for the design of reducing agents and byproduct control strategies in industrial denitration processes.