International Journal of Quantum Chemistry最新文献

Hemimorphite (Zn₄[Si₂O₇](OH)₂·H₂O) is one of the sources of zinc metal, which is commonly recovered through flotation. The presence of Ca²⁺ and Mg²⁺ ions could inevitably impact the flotation process, yet the mechanism remains unclear. In this paper, the influence of the adsorption of [Ca(H₂O)₆]²⁺ and [Mg(H₂O)₆]²⁺ on the surface properties and reagent interactions of hemimorphite was investigated using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. The results indicate that [Ca(H₂O)₆]²⁺ is chemically adsorbed through Ca-O bonding under both acidic and alkaline conditions, while [Mg(H₂O)₆]²⁺ is physically adsorbed through hydrogen bonding under acidic conditions but chemically adsorbed under alkaline conditions. Based on the work function results, [Ca(H₂O)₆]²⁺ enhances surface stability under acidic conditions, depressing sodium oleate adsorption, whereas [Mg(H₂O)₆]²⁺ has minimal impact. Under alkaline conditions, [Mg(H₂O)₆]²⁺ is more effective than [Ca(H₂O)₆]²⁺ in promoting sodium oleate adsorption. Additionally, mean square displacement results reveal that [Ca(H₂O)₆]²⁺ increases surface hydrophobicity under both acidic and alkaline conditions. However, [Mg(H₂O)₆]²⁺ decreases surface hydrophobicity under acidic conditions, while the opposite occurs under alkaline conditions. These findings elucidate the differences in mechanisms by which Ca²⁺ and Mg²⁺ ions influence the direct flotation of hemimorphite, providing a microscopic perspective for the direct flotation of hemimorphite.

According to the Bohr correspondence principle, the external temporal scalar potential in the classical equation of motion is replicated in quantum theory as a multiplicative operator. An equivalent quantum-mechanical definition of the scalar potential in Schrödinger-Pauli/Schrödinger theory is provided. The potential is a known universal functional of the wave function. At each instant of time, it is the work done in a conservative “classical” field representative of internal properties of the system: Pauli and Coulomb correlations, kinetic effects, the density, the Lorentz force, an internal magnetic component, and the current density response. The Hamiltonians are thus rewritten in a new physical manner indicative of these properties. An application to the triplet $��{�2�}^{�3�}�S�$ state of a 2-electron semiconductor quantum dot in a magnetic field is provided. The significance of the definition to the Hohenberg-Kohn theorem, and its relationship to Quantum and Kohn-Sham density functional theory, is discussed.

We present a derivation of an ab initio model potential (AIMP) based on the Van Vleck Perturbation theory. We applied the derivation to the specific case of a molecular system made of one alkali atom interacting with rare gas atoms. Our approach provides a formal background for the empirical potential often used to study this kind of molecular system and allows us to discuss their intrinsic limitations and some possible improvements. In particular, the use of AIMP, which keeps the nodal structure of the orbitals, allows us to take into account accurately the spin-orbit relativistic correction. Its application to alkali-rare gas diatomic molecules allows us to reproduce rather well the known experimental results and the best ab initio calculations at a lower computational cost.

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.