International Journal of Quantum Chemistry最新文献

In this article, we compute exponential topological indices of benzenoid hydrocarbons using MATLAB based on their edge connectivity and investigate their correlation with several thermodynamic properties, including boiling point, entropy, enthalpy of formation, Kovats retention index, octanol–water partition coefficient, and total $��\pi �$-electron energy. We develop both linear and quadratic models to predict these properties and demonstrate that the indices exhibit strong correlations with them. Notably, the correlation coefficients between most indices and the total $��\pi �$-electron energy exceed 0.98. These results suggest that exponential topological indices are effective predictors of thermodynamic properties in polycyclic aromatic compounds and may aid future research on benzenoid hydrocarbons.

Bleomycin (BLM) is the first-line clinical antibiotic used in the treatment of cancer. It inhibits DNA metabolism and is used in conjunction with other anticancer medications to treat various kinds of malignant tumors. This work focuses on examining more fully the bioactivity of BLM as both anticancer and antibacterial agents. Due to the structure–function relationship, the conformational study of the molecule was carried out first, and its potential conformations were identified. Afterwards, using the energy minimization feature of the YASARA structure program, the obtained lowest energy conformation of the molecule and the receptor taken from the protein databank (ligand-free) were optimized. BLM was subjected to molecular docking tests with two antibiotic-binding proteins (PDB IDs: 1ewj and 2zw7) to determine its action mechanism as a TN5 transposon inhibitor. Moreover, its binding affinities towards thymidylate kinase (TMK) (PDB ID: 4qgg) Escherichia coli DNA gyrase B (PDB ID: 6f86) were also evaluated to reveal its antibacterial potential. Additionally, ligand-receptor interactions were assessed via molecular dynamics (MD) process to confirm the stability of BLM docked into antibiotic binding protein (1ewj), TMK (4qgg) and E. coli DNA gyrase B (6f86) within 500 ns (for 1ewj and 6f86) or 200 ns of time (for 4qgg). Molecular mechanics/Poisson-Boltzmann Surface Area methods (MM/PBSA) were used to compute the binding energies through MD simulations. Dynamics cross correlation matrices (DCCM) analysis and principal component analysis (PCA) on the MD data were performed. Results have cleared the mechanism of action of BLM having anticancer and antibacterial properties.

The exact solution of strongly correlated systems is a computationally demanding problem, scaling exponentially with system size. Over the decades, several approximate methods have been developed to address this scaling problem. Among these, matrix product state (MPS) has emerged as physically intuitive and polynomially scaling. Methods such as density matrix renormalization group (DMRG), time evolution block decimation (TEBD), etc., use the underlying MPS wavefunction ansatz to optimize it variationally. MPS can also be utilized as a machine learning model to select the most important electronic configurations, as employed in selected configuration interactions. This work uses machine learning (ML) optimization of MPS wavefunctions to eliminate the need for multiple diagonalizations during the optimization process. We compare the performance of the machine-learned MPS-assisted selected configuration interaction approach, often mentioned as a classifier, to the machine-learned MPS wavefunction ansatz itself. While showing the viability of the machine-learned MPS ansatz, it is observed that within ML, MPS is best used as a selected configuration interaction.

Developing efficient electrocatalysts for the electrochemical reduction of CO₂ to valuable chemicals is crucial for reducing CO₂ concentration and achieving carbon neutrality. This study focuses on the nitrogen-carbon monolayer (CN) and systematically investigates the electrocatalytic CO₂ reduction reaction (CO₂RR) by introducing boron (B) as a central metal-coordination atom. We constructed 26 TM@B-CN catalysts and identified Ta@B-CN as exhibiting superior CO₂RR activity. Systematic studies revealed that Ta@B-CN not only possesses higher Faradaic Efficiency (FE) but also exhibits lower potential limitations for CO₂ reduction to CO. Compared with the computational Hydrogen Electrode (CHE), the limiting potential for the CO₂ reduction to CO on Ta@B-CN is only about −0.13 V. This research elucidates the intrinsic mechanisms of excellent catalysts through in-depth computational and electronic structure analysis. The findings provide valuable guidance for designing more efficient CO₂RR catalysts, holding significant implications for addressing climate change and advancing clean energy development.

The influence of temperature on the cross-slip conditions of <110> superpartial dislocations from the {111} glide plane to the {001} cube plane was investigated based on the elastic constants and generalized stacking fault energies of L1₂ Ni₃Al at temperatures up to 1500 K obtained by the combination of first-principles calculation with quasiharmonic approximation. The obtained values in this study are in agreement with available theoretical and experimental data. The results show that the relative stability of antiphase boundary (APB) to superlattice intrinsic stacking fault (SISF) on the {111} plane, the cross-slip driving force of 1/2<110> screw superpartials from {111} to the {001}, and the activation enthalpy required for cross-slip from {111} to {001} decrease with increasing temperature, and the APB remains stable against SISF on the {111} plane within the temperature range from 0 to 1500 K. The present results are helpful for better understanding the anomalous yield behavior of L1₂ Ni₃Al.

Zinc telluride serves as a versatile semiconductor with a broad band gap, used in many applications. The structural and optoelectronic properties of CsDyZnTe₃, CsErZnTe₃, CsHoZnTe₃, and CsTbZnTe₃ compounds have been investigated using the full potential linear augmented plane wave (FP-LAPW) method in the framework of density functional theory (DFT). All the physical properties like band structures and optical properties were calculated using the GGA + U potential. The calculated band gaps for CsDyZnTe₃, CsErZnTe₃, CsHoZnTe₃, and CsTbZnTe₃ compounds are 1.348, 1.670, 1.342, and 1.887 eV for spin-up and 0.099, 0.122, 0.098, and 0.138 eV for spin-down states, respectively, which indicates that the investigated materials are narrow band gap materials as well as direct band gap nature. When considering applications in visible light, the wider band gap materials, such as CsErZnTe₃ and CsTbZnTe₃, hold potential for utilization in light-emitting diodes (LEDs) that emit light in the visible spectrum (blue to violet region). In addition, the density of states and optical properties such as absorption coefficient, real and imaginary parts of the dielectric function, reflectivity, energy loss function, and refractive index are also calculated. There is no absorption in the infrared region; absorption starts in the visible region and increases as energy increases and reaches a maximum in the ultraviolet region. There is very small energy loss in the visible region, so the investigated material can be used in visible light applications. The reflectivity of the investigated materials is very small, which may be due to the transparent behavior of the materials in the UV region, so these compounds can be used as transparent materials.

The structural and electronic properties of Aucubin, a bioactive iridoid glycoside, were thoroughly investigated using Density Functional Theory (DFT) with the B3LYP functional and the 6-311++G(d,p) basis set. Geometry optimization, energy computations, and electronic characteristics were determined, yielding an ultimate energy value of −1261.3556 Hartree. Natural atomic charges (NAC), frontier molecular orbitals (FMO), and molecular electrostatic potential (MEP) maps were examined to elucidate the compound's reactivity and stability. Additionally, simulation-based spectroscopic analyses, including FTIR, UV–Vis, and NMR, were performed to characterize the vibrational and electronic transitions of Aucubin. The findings indicate a narrow HOMO-LUMO gap (0.16189 a.u.), suggesting significant chemical reactivity and potential applicability in photonic communication devices. This comprehensive study enhances our understanding of Aucubin's structural and electronic properties, paving the way for future applications in pharmaceutical and photonic fields.

The structures and binding energies of the Be²⁺·(N₂)_n complexes have been determined utilizing the CCSD/aug-cc-pVTZ computational method. For the mono- and di-ligated complexes, a linear configuration was observed, while tri- and tetra-ligated complexes exhibited trigonal planar and tetrahedral geometries, respectively. The sequential bond dissociation energies for these complexes were calculated, revealing a specific hierarchy: Be²⁺·N₂ > Be²⁺·(N₂)₂ > Be²⁺·(N₂)₃ > Be²⁺·(N₂)₄. This sequence corresponds to the variations in the strength of the ion-quadrupole interaction energies present in these complexes. Bond analysis of these complexes indicates that σ-donation is the primary factor influencing the observed trend in the sequential bond dissociation energies.