International Journal of Quantum Chemistry最新文献

The relativistic Thomas–Fermi model is revisited in the framework of von Weizsacker's kinetic energy functional. This model, already studied by other authors, is optimized by weighting the von Weizsacker functional with a numerical parameter and introducing a retardation term in the potential energy functional to improve its predictivity when applied to systems with a complex electronic structure. These corrections avoid overestimating the total kinetic energy and underestimating the stabilizing effect of the Coulomb potential, respectively. The model is applied to neutral and ionized atoms with increasing atomic numbers to test the qualitative and quantitative predictivity goodness of the relativistic effects. Due to the simplicity of solving the relativistic equation by numerical methods, the proposed model could be an alternative or a supportive tool to other computational methods for studying the physicochemical properties of compounds containing heavy atoms.

This study delves into the electronic, magnetic, and optical properties of Tm-doped wurtzite Al_xGa_1−xN alloys, utilizing first-principles density functional theory (DFT) calculations. By applying the LSDA+U approach to capture the strong correlation effects of 4f-Tm electrons, our findings reveal that Tm-doped Al_xGa_1−xN exhibits semiconducting behavior with inherent ferromagnetic order. Remarkably, the bandgap of Tm-doped Al_xGa_1−xN transitions from indirect to direct at an Al content (x) of 0.25, highlighting its potential for dual electrical and magnetic functionalities. The magnetic moments are highly localized at Tm sites, suggesting the feasibility of Tm as a dopant for developing AlGaN-based diluted magnetic semiconductors. Moreover, the observed spin-dependent characteristics and magnetic interactions in Tm-doped Al_xGa_1−xN underscore its applicability in spintronic devices, including spin transistors and spin logic circuits, which could significantly advance next-generation electronic systems. Additionally, the study predicts a blue shift in luminescence for Tm-doped Al_xGa_1−xN, which is attributed to the interplay between Tm dopant energy levels, Al composition, and the host alloy's band structure, as well as energy transfer and quantum confinement effects. This positions Tm-doped Al_xGa_1−xN as a promising material for applications in solid-state lighting, displays, lasers, and other optoelectronic devices requiring blue light emission.

A new series of ladder-type heteroarenes electro-optic (EO) chromophores based on unique fused oligothiophene, oligofuran, and oligopyrrole bridge with a strong push–pull effect were designed, and their distinctive electric structure and nonlinear optical (NLO) properties were investigated by multiple methods, including DOS analysis, CPKS method, SOS model, TSM model, and hyperpolarizability density analysis. Interestingly, it is found that the introduction of different strengths of donor and acceptor moieties, the nature of ladder-type heteroarenes bridge, and the medium polarity play critical roles in achieving ultra-large hyperpolarizabilities. Encouragingly, the DN1-6Fu-AS1 and DN1-6Py-AS1 both exhibit ultra-large β_prj values (up to 12965.5 × 10⁻³⁰ esu) and β_tot value (up to 13238.2 × 10⁻³⁰ esu), owing to their exceptionally low transitions energy and large variation of dipole moment. The DO2-6Fu-AO2, DO2-6Th-AO2, DO2-6Fu-AS1, and DO2-6Th-AS1, exhibit very deep HOMO levels, which are expected to have superior air stability and effectively prevent large leakage currents. Hirshfeld surface analysis and interaction region indicator analysis were employed to explore the noncovalent interactions in the dimer. The DO2-6Fu-AS1 and DO2-6Py-AS1 show the outstanding electro-optical Pockels effect, and DN1-6Fu-AO2 exhibit large SHG responses. These unique and brand-new push-pull ladder-type heteroarenes chromophores are promising candidates for chip-scale EO modulators, and electronic and photonic devices in emerging communication, energy, analog, and digital technologies.

This investigation employs first-principles calculations to explore the interaction between imidazolium ionic liquids (ILs) and fluoride additives on lithium metal surface. Our focus lies in the comprehensive analysis of three distinct categories of fluorinated additives, each differing in their degree of fluorination. The computations reveal that fluorination plays a significant role in determining both the ionic conductivity and the formation of the solid–electrolyte interphase (SEI) film. Specifically, heightened fluorination enhances the oxidative stability of the system but diminishes the strength of solvent binding, resulting in the formation of larger salt/anion clusters and a decrease in ionic conductivity. Conversely, increased fluorination facilitates the interaction between fluorinated additives and the lithium metal surface, thereby aiding in the formation of a stable SEI film characterized by an abundance of inorganic LiF components. This is important as it serves to suppress dendrite growth and mitigate interface side reactions. Considering the combined influences of ionic conductivity and film formation, 1FP is suggested as the optimal candidate for pyridine-based additive systems, with FEC preferred for cyclic ester-based additive systems and BC for chain ester-based additive systems. This study provides theoretical references for the design of ionic liquid-fluorinated additive electrolyte systems that can protect the lithium metal anode.

The Pὃschl–Teller potential is a molecular potential energy function that has only been reported for bound state. This Pὃschl–Teller potential is a good representation of many molecules and has not been examined for any thermodynamic property irrespective of its fitness for molecular study. In this study, the molar entropy of four molecules (Pbr, BBr, CsCl, and CsO molecules) is calculated via the molar partition function. The predicted results are compared with the experimental data recorded in the National Institute of Standards and Technology (NIST) database. It is noted that the predicted values for the studied molecules perfectly agree with the experimental results with the following average absolute percentage deviation, PBr is 0.0158%, BBr is 0.0053%, CsCl is 0.0020%, and CsO is 0.0052%. The present model reproduces better results for CsCl and CsO molecules compared to the shifted Tietz–Wei potential and improved Tietz-oscillator previously reported whose average absolute percentage deviation are 0.361% and 0.284% for CsCl and 0.272% and 0.228% for CsO, respectively.

The problem of characterization of all graphs where the deletion of an edge results in decrease or increase in the energy is far from completion. To be more exact, we solve this problem for Inverse Sum Indeg energy. We compute the ISI energies of edge deleted graphs of $��{�K�}_{�n�}�$, $��{�K�}_{�n�,�n�}�$, $��{�K�}_{�n�,�n�,�n�}�$, and star graph, finally we compare the respective energies from the original graphs. We give different graphs where both cases can happen. This serves as partial solutions of the modified version of the hard to crack problem posed by Gutman to characterize all graphs whose energy decreases after deletion of an edge.

In this work, we set a series of blue-P/Hf₂CO₂ vdW heterostructures by stacking blue-P and Hf₂CO₂ monolayers together. Then the most stable structure, the AD-stacking blue-P/Hf₂CO₂ vdW structure (the HS), is selected out for further investigation. The electronic and optical properties of the HS are studied for exploring its potential applications. Result of its electronic structure investigation indicates that the HS is a type-I band arrangement. By applying different biaxial strains parallel to the stacking direction to the HS, we regulate its band gap and band edge positions. Results show a suitable strain not only can adjust the band alignment type of the HS change from type-I to type-II but also regulate the band structure to a suitable band edge positions for photocatalytic water splitting. The band edge position of HS (2%) across the oxidation and reduction potential indicates that it is a potential photocatalyst of water splitting at pH = 7. By calculating the absorption coefficient, we found the HS (2%) has a good light-harvesting ability in visible light and UV region, which further proves it has the potential as the sunlight-driven photocatalyst for water splitting.

The Schrödinger equation for simple homonuclear and heteronuclear diatomic molecules is analytically solved using one-parameter Slater-type orbitals (STOs) to approximate the electronic wave function within a molecular orbital (MO)-like approach. The resulting total energies, equilibrium bond lengths, potential curves, and electron densities are presented in detail. Calculations using a selected orbital exponent accurately reproduce results from standard methods. Furthermore, the optimization of the orbital exponent allows for a more accurate representation of the electronic wave function, leading to the improved results of the total energy and the equilibrium bond length, as well as minimal computational cost. Seen in the heteronuclear diatomic molecule, the use of the one-parameter STOs allows the transformation of the heteronuclear problem into the homonuclear one, revealing the electron repulsion effect on the orbital exponent parameter.

Transparent conducting oxides (TCOs) from the semiconductor family have garnered considerable interest due to the growing popularity of optoelectronic and thermodynamical applications. Our present study has presented findings on the electronic, optical, and thermodynamic characteristics of spinel oxide MnGa₂P₃H₄NO₁₄; using density functional theory (DFT), we utilized first-principles calculations carried out with the Wien 2 k software package. The calculations were performed using the generalized-gradient-approximation plus Hubbard potential U (GGA+U) method for the doped materials. The band structure calculation reveals that the parent compound exhibits a semiconducting nature and a direct band gap of 2.9 and 1.7 eV for spin-up and down channels, respectively. The stability of the material is assessed by evaluating its formation energies, which reveal that spinel oxide exhibits the highest stability. The thermodynamic properties are determined using the quasiharmonic Debye model, implemented in the GIBBS 2 code. Furthermore, the quasiharmonic Debye model examines the pressure and temperature dependence of all parameters related to the investigated spinel oxides. In order to evaluate the effectiveness of the radiation shielding, we computed the mass attenuation coefficient for the XCOM program that was investigated from the sample. In addition, linear attenuation, half-value layer, and mean free path values have been evaluated. A thorough investigation into the dielectric function's optical characteristics was conducted. It has been found that the dielectric function exhibits a wide range of energy transparency. The discovery of UV-absorbing materials with extremely narrow band gaps suggests their potential use in optoelectronic and solar cell applications. These results provide solid proof and motivation for seeking cutting-edge optoelectronic materials and technology.

Molecular geometry and harmonic frequency calculations are essential in thermochemical computations, with density functional theory (DFT) being widely employed for vibrational frequency predictions due to its efficiency and accuracy. In this study, we assessed the precision of 28 Minnesota based functionals with three different basis sets using the VIBFREQ1295 dataset. Scaling factors are necessary for predicting fundamental frequencies, global scaling factors were fitted by using F38/10 and VIBFREQ1295 datasets. The superior performing functionals were then fitted based on vibrational frequency ranges to obtain frequency-range-specific scaling factors. We observed consistent outlier across various model chemistries in vibrational frequency predictions, with alternative scaling factors showing minimal impact on reducing outlier occurrences. Besides, large basis sets are not indispensably required for fundamental frequency predictions. M06-L, revM06-L, SOGGA11-X, PW6B95-D3(BJ), CF22D, and M06-2X consistently exhibit excellent performance across the three basis sets. When using frequency-range-specific scaling factors, the root mean squard errors (RMSEs) and median absolute errors (MedAEs) of almost all the selected functionals were reduced. PW6B95-D3(BJ), CF22D, and MN12-SX exhibited the lowest RMSEs. Comparisons were also done for different data classifications; the dataset was classified by the elements of the molecules, vibrational frequency intervals, and vibrational modes.