International Journal of Quantum Chemistry最新文献

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.

The properties of the output probe field in a qubit-embedded system containing two coupled cavities are investigated theoretically. A strong pump field and a weak probe field drive the left cavity. The right cavity couples the mechanical oscillator through the photothermal effect. Simultaneously, a qubit couples the right cavity and the mechanical oscillator through Jaynes-Cummings coupling. Coupled-resonator induced transparency (CRIT) is realized in the bare coupled cavities firstly. When considering the photothermal effect, photothermally induced transparency (PTIT) can also be achieved. Further, when a qubit is inserted, the qubit-assisted induced transparency (QIT) is demonstrated. Tunable optical response, along with slow-fast light at different frequencies, is shown by adjusting the system coupling strengths and frequency detunings. Especially, we demonstrate the group delay in the PTIT can also be manipulated by the photon tunneling between the double cavities.

Quaternary Heusler LiTiRhZ (Z = Si, Ge, Sn) compounds are investigated for mechanical and thermodynamic stability and their suitability as potential thermoelectric materials in a high-temperature range. The density functional theory and Boltzmann transport equations have been used for the calculations of structural, electronic, phonon dynamics, elastic, and thermoelectric properties. The compounds exhibit indirect band gaps of 1.076, 1.132, and 1.032 eV in LiTiRhZ (Z = Si, Ge, Sn), respectively, confirming their semiconducting nature. The negative formation energies and high melting points (~1800 K) suggest structural stability and experimental feasibility. Elastic and phonon calculations confirm mechanical and dynamical stability, along with ductile and anisotropic behavior. For a better understanding of thermodynamic properties, free energy, entropy, and specific heat at constant volume are also investigated up to 1000 K temperature. We obtained the increasing nature of power factor in all studied compounds, indicating the high value of figure of merit (ZT), particularly in the high-temperature region, with LiTiRhSi achieving a maximum ZT ~ 0.69 at 1000 K, showing its potential for high-temperature thermoelectric applications. The higher and stable values of ZT as compared to the other reports in the high-temperature range may provide strong support for experimental research on the studied compounds.