International Journal of Quantum Chemistry最新文献

The low-cost and highly active FeN₄C single-atom catalyst is currently one of the most promising oxygen reduction catalysts for replacing the precious metal catalysts in fuel cells. The electron occupation states of Fe 3d orbitals have been proved to play a determining role in the catalytic activity of FeN₄C. Herein, by adding the second transition-metal atom M to form FeMN₆C, we modulate the 3d-orbital splitting and spin states of Fe to uncover the spin effects on the adsorption energies of oxygen-containing intermediates and catalytic activity. The results reveal that the introduction of M gives rise to various electron occupation states and magnetic moments of the Fe atom, tuning the catalytic activity of FeN₄C. Among them, FeRhN₆C and FePdN₆C have low theoretical ORR overpotentials of 0.41 and 0.42 V. It is found that there is a volcano relation between the spin moments of Fe and the adsorption energies rather than the linear relation reported in other work.

Quaternary semiconductors based on copper offer special characteristics such as strong thermoelectric stability and tunable optical response. Here, the multifaceted association between the structure, optoelectronic and transport properties of direct band gap novel BaCuMF (M = S, Se) quaternary semiconductors was examined employing the recognized density functional theory. The formation energies show the stability of these materials and are much lower than the corresponding elemental hulls. Strong correlations were found between the ionicity in the Ba–X bindings and the formation energy, suggesting that these materials share a low formation energy with other ion bindings. BaCuSF showed greater resistance than BaCuSeF, which led to differences in the strength of bonds between the atoms. With TB-mBJ and PBE-GGA, the band structure estimates are 2.69, 1.28 for BaCuSF, and 2.64, 1.62 eV for BaCuSeF, respectively. These materials were found advantageous for tunable device applications due to their wide absorption spectrum. The significant and remarkable thermoelectric properties of the examined materials indicate their suitability for thermoelectric applications. Their potential application in cutting-edge optoelectronic devices can be established by the current work, opening up innovative technological possibilities.

Building van der Waals heterostructure is an effective method to design multiferroic materials. Here, by performing first principles calculations, we study the electronic and magnetic properties of CuCrP₂S₆/CuInP₂S₆ (CCPS/CIPS) heterostructure composed of ferroelectric (FE) CuInP₂S₆ and multiferroic CuCrP₂S₆. It is shown that CCPS-P↓/CIPS-P↓ is a ferromagnetic (FM) half metal, with the band alignment of type II in the spin-down channel, while for CCPS-P↑/CIPS-P↑, CCPS-P↑/CIPS-P↓, and CCPS-P↓/CIPS-P↑, they are all FM semiconductors with type II band alignment. Moreover, the electronic properties of CCPS/CIPS can be changed under biaxial strains; that is, CCPS-P↓/CIPS-P↓ can change from FM half metal to FM semiconductor, and CCPS-P↑/CIPS-P↑, CCPS-P↑/CIPS-P↓, and CCPS-P↓/CIPS-P↑ have shrinking band gaps in both spin channels under biaxial strains. Such characteristics suggest CCPS/CIPS heterostructure can be potential nonvolatile memory device materials.

Iron-sulfur (FeS) clusters play a crucial role in biological redox processes. In this study, we evaluate the accuracy of various electronic-structure methods for calculating the redox potentials of the synthetic [Fe₄S₄(SC(CH₃)₃)₄] cluster by comparing them to experimental data. Our assessment includes a range of density functionals within broken-symmetry density functional theory (BS-DFT), the most commonly used approach for this purpose, though it has not yet been systematically compared to other methods. We also explore correlated methods such as the random phase approximation (RPA) and auxiliary-field quantum Monte Carlo (AFQMC), which are rarely applied to FeS clusters, as well as complete active space (CAS) methods combined with density matrix renormalization group (DMRG) theory and various active space constructions. Among these, BS-DFT with the hybrid functionals B3LYP, PBE0, and TPSSh showed the highest accuracy, together with RPA in combination with the approximate exchange kernel (AXK). While AFQMC demonstrated some promise, DMRG-CAS methods were significantly less accurate, likely due to inconsistencies between the active spaces within a redox pair.

This study employs density functional theory (DFT) to investigate the effects of Mg substitution on SrNbO₃ and its oxygen vacancy defect variants, providing a comprehensive analysis of their structural, mechanical, electronic, and thermal properties. Structural optimization, mechanical stability assessment, and enthalpy of formation calculations confirm the overall stability of the doped systems. The results reveal that Mg incorporation enhances thermal conductivity and reduces stiffness, attributed to induced anharmonicity, while preserving the metallic nature of SrNbO₃. Band structure analysis indicates that the electronic properties are predominantly governed by Nb-O p-d hybridization, with minimal direct influence from Mg doping. Furthermore, the study highlights the crucial role of oxygen vacancies in modulating transparency, demonstrating their impact on optoelectronic performance and material growth dynamics, similar to effects observed in literature-reported SrNbO₃ doped structures and oxygen variants. These findings suggest that Mg-doped SrNbO₃ holds significant potential for advanced optoelectronic applications and next-generation transparent conducting materials.

Inspired by the solvent-polarity-dependent novel luminescent materials, in this work, the effects of solvent polarities on the excited-state intramolecular proton transfer (ESIPT) process of H₂BP-(OH)₂DC are systematically investigated, based on DFT and TDDFT methodologies. We mainly focus on elucidating the ESDPT mechanism in H₂BP-(OH)₂DC compound. By analyzing the geometrical configurations, infrared (IR) vibrational spectra, and core-valence bifurcation (CVB) indexes, we could first verify the enhancement of intramolecular dual hydrogen bonding interactions in the first excited state. Meanwhile, we also pay attention to the HOMO and LUMO orbitals to check the effects of charge redistribution on facilitating the ESIPT/ESDPT process. The potential energy surfaces (PESs) are also scanned to confirm the stepwise ESDPT mechanism for H₂BP-(OH)₂DC system. We further propose that the increase of solvent polarity can promote the process of the step-by-step ESDPT reaction processes for H₂BP-(OH)₂DC fluorophore dependent on the computational potential energy barriers for H₂BP-(OH)₂DC in cyclohexane, chloroform, and acetonitrile solvents.

The advancement of magnesium ion batteries necessitates the exploration of novel high-capacity anode materials. This research examines the viability of HfSe₂ monolayers as a potential anode material for magnesium ion batteries, utilizing first-principles calculations. The findings indicate that HfSe₂ demonstrates substantial electrical conductivity as an electrode material, with its electronic conductivity remaining unaffected by applied strain. Additionally, a low diffusion barrier of 0.071 eV contributes to its high rate performance. Notably, HfSe₂ possesses a significant theoretical capacity of 480.735 mAh/g, accompanied by a relatively low open circuit voltage of 0.203 V. These results provide insights into the magnesium storage mechanism of HfSe₂ monolayers and inform the design of magnesium ion batteries.