International Journal of Quantum Chemistry最新文献

To obtain the thermal decomposition mechanism and key intermediates of pyrazolo-triazine fused-ring skeletons (PT1∼PT10), the decay pathways were studied by using the M062X method for optimization and DLPNO-CCSD(T)/cc-pVTZ methods for energies. Results showed that the most stable structure of the pyrazolo-triazine fused-ring is characterized by a structure with two CH bonds connected on the triazine ring (PT9). Notably, the H transfer has become the main reaction to promote the ring-opening reaction. The introduction of the O atom changes the dominant reaction pathway. Except for PT9 and PT10, the position arrangement of N atoms in the molecule significantly affects its decomposition path and stability. On the one hand, structures containing three or more N atoms directly connected are the most likely to undergo a ring-opening reaction, while other structures tend to undergo H transfer reactions. On the other hand, an increase in the number of N atoms directly connected further reduces the stability. These conclusions were expected to contribute significantly to the design and application of novel high energy density materials.

4-Methoxychalcone (4MC) is investigated for its potential as an acetylcholinesterase (AChE) inhibitor to treat Alzheimer's disease (AD). We investigated the electrical, vibrational, and structural properties of 4MC with computational and spectroscopic methods. In order to improve the molecular geometry, investigate the stability and reactivity of the chemical in both gas and DMSO phases, density functional theory (DFT) was performed using the B3LYP/6-311++G(d,p) basis set. Potential energy surface (PES) analysis identified the most stable conformer. Experimental methods such as FT-Raman, FT-IR, x-ray diffraction (XRD), UV–Vis, and NMR spectroscopy were employed to verify the computational predictions. Comparing the measured UV–visible spectra with the theoretical time-dependent DFT-calculated spectra is a good instance. Analysis of the molecule's reactivity and electron transfer behavior was done by looking at its frontier molecular orbitals. In the gas phase, a HOMO-LUMO energy gap of ∼3.84 eV suggests relatively high chemical reactivity, which could contribute to potential bioactivity. Intermolecular interactions and charge transfer properties were revealed by the investigations of Hirshfeld surface, Mulliken charge, natural bond orbital (NBO), and molecular electrostatic potential (MEP). The wave function-based topology investigations, including localized orbital locator (LOL), electron localization function (ELF), Reduced Density Gradient (RDG), and non-covalent interaction (NCI) characteristics, have been extensively studied. Molecular docking revealed a strong binding affinity of 4MC (−9.8 kcal/mol) with AChE, comparable to that of the standard drug donepezil. Molecular dynamic (MD) simulations confirmed complex stability through root mean square deviation (RMSD), root mean square fluctuation (RMSF), and radius of gyration (R_g). Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) results showed favorable pharmacokinetics with good BBB permeability, high intestinal absorption, and low toxicity, supporting 4MC's potential as a candidate for Alzheimer's therapy.

This study explores the adsorption properties of Li- and Na-decorated C₂₄N₂₄ nanocages and their interactions with SO₂, SCO, H₂S, CS₂, HCHO, and CH₄ gas molecules. The introduction of Li and Na atoms significantly enhances gas adsorption due to increased binding energies and modified electronic properties. The adsorption of SO₂, SCO, H₂S, CS₂, HCHO, and CH₄ on Li-and Na-decorated C₂₄N₂₄ demonstrates varying interaction strengths compared to pristine C₂₄N₂₄. The decorated nanocages exhibit altered electronic structures, with changes in energy gaps and charge transfer upon gas adsorption. Frontier molecular orbital analysis indicates improved reactivity, suggesting potential suitability for gas sensing applications. However, recovery times reveal limitations in sensing abilities for certain gases. The ΔG for all gases adsorbed on C₂₄N₂₄, Li- and Na-decorated C₂₄N₂₄ at 298.15 K and 1 atm are nonspontaneous, except for SO₂ and HCHO on Li- and Na-decorated C₂₄N₂₄. The results demonstrate that Li- and Na-decorated C₂₄N₂₄ nanocages exhibit high sensitivity and fast desorption for SO₂, highlighting their potential for practical gas sensing applications.

The significance of Mg₂Zn₁₁ in Zn-Mg alloy systems has sparked considerable interest. In this work, the phase stability, elasticity, electronic characteristics, and thermal conductivity of Ca-doped Mg₂Zn₁₁ were explored based on the first-principles calculations. The calculated results show that doping with Ca at the 2Mg and 4–6Mg sites enhances the stability, Ca doping changes the elastic properties, and increases the ductility of Mg₂Zn₁₁. Moreover, Ca doping changes the elastic anisotropy in different directions. Besides, doping Ca at the 1Mg–4Mg sites also improves the thermal conductivity of Mg₂Zn₁₁. These findings shed light on the potential benefits of doping in enhancing the overall performance of Mg₂Zn₁₁ in Zn-Mg alloys.

The construction of active sites with low loadings of noble and nonnoble metals is regarded as a promising strategy for the rational design of catalysts. Herein, we investigated the Pt-doped Co(111) surfaces and the characteristics of CO adsorption on Pt_n/Co(111) (n = 0–3) using Density Functional Theory. The research results indicate that the stable structures with surface cobalt atoms substituted by platinum atoms have a platinum coverage not exceeding 1/2 ML. In addition, an examination of the adsorption behavior of CO on Pt_n/CO (111) (n = 0–3) surfaces was conducted. The determined adsorption energies for CO on four surfaces were −1.707, 1.712, −1.667, and −1.647 eV, respectively. Notably, the sequence of adsorption energy is as follows: Pt/Co(111) > Co(111) > Pt₂/Co(111) > Pt₃/Co(111). The study confirms that optimal CO adsorption energy on the Co (111) surface is achieved with a single Pt atom doping, indicating potential for high catalytic activity even at low rates of Pt loading.

In this work, we investigate quantum information entropy for double hyperbolic well potentials within the framework of the fractional Schrödinger equation (FSE). Specifically, we analyze the position and momentum Shannon entropies for two hyperbolic potentials, $��{�U�}_{�1�}�$ and $��{�U�}_{�2�}�$, as a function of the fractional derivative order $��\mu �$. Our findings reveal that decreasing $��\mu �$ enhances wave function localization in position space, thereby reducing spatial uncertainty while simultaneously increasing momentum uncertainty. We confirm the validity of the Beckner–Bialynicki-Birula–Mycielski inequality for both potentials, demonstrating its robustness across different degrees of nonlocality. Furthermore, we explore the behavior of Fisher information, observing that it increases in position space while decreases in momentum space as the well depths grow.

The electronic and nonlinear optical (NLO) properties of XAl₁₂-Y (X = Be, Al, C, and P; Y = K and K₃O) were systematically investigated theoretically. Density functional theory calculations demonstrated that the Y ligands bind strongly to the XAl₁₂ clusters with high binding energies. Natural population analysis revealed that an electron is transferred from (super)alkali to the XAl₁₂ cluster. XAl₁₂-Y exhibits excellent NLO response, as evidenced by the calculated static and dynamic first hyperpolarizabilities, as well as hyper-Rayleigh scattering (HRS) hyperpolarizabilities. The NLO responses critically depend on the XAl₁₂ core and ligand type, with PAl₂-K, CAl₁₂-K₃O, and PAl₁₂-K₃O showing superior performance. The remarkable NLO responses of these systems primarily arise from (super)alkali ligands, underscoring the critical role of ligand introduction in enhancing the NLO response of the system. This work demonstrates that combining potent (super)alkalis with tunable superatom acceptors is a highly effective strategy for designing high-performance NLO materials.

The trans-to-cis photoisomerization behavior of azobenzene endows them with excellent photo-switching potential, and the modulation of the conjugated system can effectively optimize their nonlinear optical (NLO) responses and switching efficiency. In this study, we systematically investigated, through density functional theory (DFT) calculations, the effects of conjugation length and the position of the NN bond on the electronic structures, excited-state properties, and NLO performances of azobenzene derivatives modified with –NH₂ and –NO₂ groups. The results indicated that extending the conjugated system significantly reduced the HOMO-LUMO energy gap. When the NN bond was near the –NO₂, the charge transfer efficiency was notably enhanced, and the static first hyperpolarizability of the trans configuration reached up to 17.54 × 10³ a.u. Additionally, the synergy between conjugation elongation and the position of the NN bond improved the photo-switching efficiency, which could be as high as 3.28 in that of the 2–2 system. Moreover, having the NN bond adjacent to the –NO₂ lowered the isomerization energy barrier, further optimizing the photo response properties. This work provides a theoretical basis for designing high efficient photo-switching materials.