International Journal of Quantum Chemistry最新文献

Utilizing the reactive molecular dynamics (ReaxFF MD) simulation, we conducted a comprehensive study on the impact of basicity (OH⁻/Al³⁺ ratio), concentration, and temperature on the hydrolysis and polymerization reactions of Al³⁺-solvated molecules. Through simulations, we analyzed the structural changes, energy fluctuations of the system, and the evolution patterns of reaction products under different parameters, which were subsequently validated by experimental data. The research results indicate that hydroxide ions in the solution directly influence the breakage of OH bonds in the coordinating water molecules of solvated aluminum ions. This, in turn, affects the number of H₂O and OH⁻ ions coordinated with Al³⁺, leading to changes in hydrolysis products. Additionally, the number of OH⁻ ions surrounding Al³⁺ affects the electrostatic repulsion, making it easier for polymerization reactions to occur as the system approaches the point of zero charge. On the other hand, an increase in concentration and temperature enhances the frequency of cluster collisions, thus contributing to an increase in polymerization degree. The experimental results align closely with our simulated predictions. As the pH value increases, the particle size exhibits a trend of first increasing and then decreasing, reaching a maximum at the point of zero charge. Simultaneously, an increase in concentration also prompts an increase in particle size. The combination of these empirical results with simulations enhances the credibility and reliability of our model's predictive capabilities. This study not only expands our understanding of the relevant chemical reaction processes but also provides important theoretical support for practical applications in related fields.

Spectrum-based topological indices (eigenvalue-based topological indices), a valuable tool for analyzing molecular structure. These topological indices are metrics that reflect the inherent characteristics of chemical substances, were employed in conjunction with quantitative structure-property relationship (QSPR) to investigate nonsteroidal anti-inflammatory drugs (NSAIDs) which are used toalleviate or eliminate pain sensations in affected areas. We have to use mathematica to compute various eigenvalue-based indices and utilized statistical software to identify correlations between these indices and key physical properties of NSAIDs. The analysis revealed that specific indices, including $��{�E�}_{�F�Z�S�}�$ index, $��{�\rho �}_{�F�Z�S�}�$ index, $��{�E�}_{�I�S�I�S�}�$ index, and $��{�E�}_{�A�B�C�S�}�$ index exhibited strong associations with properties like complexity and refractivity, boiling point, polarity, and molar weight, respectively.

This study explores the reaction mechanism between [(BDI)Ca(μ-H)]₂ and cyclopentadiene (C₅H₆). By analyzing the reaction pathways, it is found that compared with the traditional CaH/CC insertion reaction of polyenes with [(BDI)Ca(μ-H)]₂, C₅H₆ is more inclined to undergo a CaH/CH₂ dehydrogenation reaction, resulting in more stable cyclopentadienyl complexes. The subsequent reactions also tend to continue with dehydrogenation to form dimeric complexes. The aromatization process of C₅H₆ is a key factor driving this reaction trend. This result provides a new perspective for understanding the catalytic behavior of calcium hydride derivatives and can help in the design and synthesis of new catalysts and functional materials based on such compounds.

The analysis of various chemical structures can be done by using topological indices (TI), graph polynomials, and other useful tools that graph theory offers. The mathematical entries called TI are subtracted from the chemical structure. In this article, we investigate the neighborhood degree based topological indices of $��T�U�{�C�}_{�4�}�{�C�}_{�8�}�\left(�R�\right)�$ nanotube via direct and NM-polynomial. The indices which we have computed are first, second, third, fourth, fifth NDe indices, third version of Zagreb index, neighborhood second Zagreb index, neighborhood second modified Zagreb index, neighborhood forgotten topological index, neighborhood general Randic index, neighborhood inverse sum index, fourth atom bond connectivity index, fifth geometric arithmetic index, fifth arithmetic geometric index, fifth hyper first and second Zagreb index.

Based on irreducible representations of generalized quaternion groups, closed-form formulae of Kirchhoff indices and resistance distances between vertex pairs of Cayley graphs on these groups are given.

To understand the nature of heterogeneous catalytic processes and improve their efficiency, it is necessary to conduct both experimental and theoretical studies. At the same time, there is no unified approach to obtaining the necessary data using quantum chemistry methods. In this work, problems of the existing calculational approaches are analyzed. The obtained information is used to develop the original three-layer embedded cluster model approach, which is shown to be the most effective. The general algorithm for obtaining such models for various oxides is formulated. The sufficient accuracy of the proposed models in predicting geometric and energy characteristics, vibrational frequencies, activation barriers, and thermodynamic characteristics is verified. The specifics of calculating the thermodynamic characteristics of heterogeneous processes using the proposed cluster models is studied in detail. The developed approach is an effective tool for studying the mechanism of heterogeneous catalytic processes both by itself and in combination with experiment.

This study solves the radial Schrödinger wave equation (RSWE) with the improved Rosen–Morse (IRM) potential constrained by an electromagnetic field. Energy eigenvalues are derived using the parametric Nikiforov–Uvarov method and Pekeris approximation. The internal partition function, isobaric molar heat capacity formula, and magnetization model are then deduced from the equation governing pure vibrational energy states. These analytical models are applied to several pure substances, specifically Br₂ (X ¹Σ_g⁺), BrF (X ¹Σ⁺), ICl (X ¹Σ_g⁺), and P₂ (X ¹Σ_g⁺) molecules. Numerical approximations of the energy eigenvalues for these molecules closely match their exact values. The isobaric molar heat capacity expression yields mean percentage absolute deviations of 1.6585%, 0.9162%, 1.2193%, and 0.7232% when compared against experimental data for Br₂ (X ¹Σ_g⁺), BrF (X ¹Σ⁺), ICl (X ¹Σ_g⁺), and P₂ (X ¹Σ_g⁺), respectively. These results align well with other heat capacity models in existing literature.

Experimental and theoretical studies over the recent years have shown that noncovalent interactions play a crucial role in diverse chemical and biological processes. Noncovalent interactions have been recognized as significantly contributing towards stabilizing various supramolecular species. We have attempted to interpret computationally the nature of various noncovalent interactions between the aromatic surfaces of 6-phenyl-1,3,5-triazine and biphenyl with polar as well as non-polar molecules such as H₂O, HCl, HF, CO₂, and so forth and adding the inter-aromatic rings π-stacking, using the r²SCAN-3c/DEF2-mTZVPP model chemistry. Energy decomposition analysis with the SAPT method shows that the electrostatics and dispersion components play crucial roles in stabilizing these complexes whereas induction and polarization play minor roles.