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In this work, we report the results from our spectroscopic study on AlF and AlCl molecules. We carry out detailed electronic structure calculations in both the molecules, including obtaining the potential energy surfaces of the X 1 Σ ground electronic state and some of the low-lying excited electronic states belonging to Σ and Π symmetries. This is followed by evaluating the spectroscopic constants and molecular properties such as electric dipole moments and electric quadrupole moments. Throughout, we employ the multi-reference configuration interaction method and work with high-quality quadruple zeta basis sets. Further, transition dipole moments between the ground electronic state and singlet excited states are also studied. The relevant vibrational parameters are computed by solving the vibrational Schrödinger equation. Subsequently, the vibrational energy spacings and transition dipole moments between the vibrational levels belonging to the same electronic states are used to evaluate the spontaneous and black-body radiation-induced transition rates, followed by computing the lifetimes. Finally, the energy differences between rotational levels belonging to different vibrational levels and within an electronic state as well as the Einstein coefficients are reported. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes (SWCNTs) are ideal channel material candidates for energy-efficient nanoscale transistors; however, it is challenging to achieve uniform alignment of semiconducting SWCNTs with homogeneous chirality. Here, we report the proof-of-concept of using organized chirality-sorted SWCNTs via the alignment relay technique (ART), where iptycene molecules order the nanotubes through π–π interactions. Top-gated field-effect transistors (FETs) were fabricated with aligned (10,3) chirality SWCNTs as channels to show an ION of 3.8 μA, an ION/IOFF ratio of 2.9 × 106, and a carrier mobility of 10.08 cm2/(V s), which is enhanced by two magnitudes of order compared with a bundled SWCNT network channel. In addition, the ART was applied to align commercially available semiconducting SWCNTs to fabricate a chemiresistive gas sensor that showed prompt detection of 4 ppm ammonia (NH3) with a sensitivity of 0.43 ± 0.04%/ppm, demonstrating a general approach to align SWCNTs for applications in electronic devices. [ABSTRACT FROM AUTHOR]

The regulation of solution pH on the structural and optical properties of peptide self‐assemblies remains a critical yet unresolved issue in peptide research. This study investigates the heptapeptide Ac‐IHIHIQI‐NH2 and its intrinsic fluorescence across a range of pH levels, demonstrating that variations in pH lead to significant changes in the morphology of the self‐assembled structures. While the position of the fluorescence emission remains constant—due to the stability provided by the hydrogen bonding network of the peptide backbone—the intensity of the fluorescence exhibits a direct correlation with the degree of self‐assembly. This finding underscores a dynamic relationship between structural morphology and optical properties. Notably, the ability of the peptide to self‐assemble under diverse pH conditions is a novel observation that contrasts with previously reported literature. By employing a computationally driven approach, complemented by rigorous experimental validation, this work establishes a new paradigm for studying complex interacting systems such as peptide self‐assembly. Our findings enhance the understanding of how environmental factors influence peptide behavior and pave the way for the design of innovative peptide‐based materials with tunable optical characteristics, with potential applications in bioluminescent probes and diagnostic tools for neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

The priority of research efforts over the past two decades has been focused on the effective detection of harmful gases and the development of small, efficient, and reliable nanodimensional sensors. The adsorption of carbon monoxide (CO) gas molecules on zigzag gallium phosphide nanoribbons (zGaPNRs) has been studied using first-principle calculations within the context of Density Functional Theory (DFT). Here, we have evaluated the potential of single-atom thick zGaPNRs in different configurations of nanoribbons for the detection of CO. Many possible configurations of studying the CO molecule adsorption on zGaPNRs have been explored. It is established that the interaction of CO molecules has an impact on the electrical and transport properties of zGaPNRs. The H-GaP-H is the most stable structure with the binding energy ( E b ) of −5.70 eV. The stability is compromised with CO adsorption with CO-GaP-CO being the least stable structure. Pristine structure is semiconducting with the energy band gap ( E G ) of −3.95 eV. The computed sensitivity (S) values are found to be highest for Co-GaPNRs with the S value of 1. 7 7 × 1 0 1 8 and the least sensitive structure is H-GaP-CO with the computed S as 3. 8 4 × 1 0 1 7 . Additionally, it is noted that CO molecules always establish a stable chemical bond with the nanoribbon edges through the C-side. The unique behavior is revealed by the transport characteristics, which demonstrates that when CO adsorption occurs near the Ga edge, the current magnitude is noticeably greater. Our research demonstrates the potential of specific CO adsorption and detection for the development of nanosensors. [ABSTRACT FROM AUTHOR]

The development of molecular switches with tunable properties has garnered considerable interest over several decades. A novel spin‐crossover (SCO) material based on iron(II) complexes incorporating 4‐acetylpyridine (4‐acpy) and [Hg(SCN)4]2− anions was synthesized and formulated as [Fe(4‐acpy)2][Hg(μ‐SCN)4] (1). Compound 1 is crystallized in a three‐dimensional network in the non‐centrosymmetric orthorhombic space group Pna21 with two octahedral [Fe(4‐acpy)2(NCS)4] entities featuring two distinct Fe centers (Fe1 and Fe2). Crystallographic, magnetic, and Mössbauer measurements reveal an incomplete SCO exclusively at Fe2, with transition temperature T1/2≈102 K. Photomagnetic studies conducted at 10 K with lasers ranging from 405 to 1310 nm evidence light‐induced excited spin‐state trapping (LIESST) and reverse‐LIESST effects, with a unique near‐infrared‐responsive LIESST phenomenon at 1064 and 1310 nm. Advanced photocrystallographic studies at 40 K provide precise structural evidence for these metastable states. The optical and vibrational properties consistently corroborate with magnetic and photomagnetic studies. Additionally, temperature‐ and light‐dependent terahertz (THz) absorptions are associated with phonon vibrations around Fe2 centers, through SCO behavior, as supported by ab initio calculation. The Fe(II)−Hg(II) systems can be promising benchmarks for exploring synergistic switching effects in structural, magnetic, and spectroscopic properties. [ABSTRACT FROM AUTHOR]

Herein, a self‐supported, robust, and noble‐metal‐free 3D hierarchical interface‐rich Fe‐doped Co‐LDH@MoS2‐Ni3S2/NF heterostructure electrocatalyst has been prepared through a controllable two‐step hydrothermal process. The resultant electrode shows low overpotential of ~95 mV for hydrogen evolution reaction (HER), ~220 mV for the oxygen evolution reaction (OER), and the two‐electrode system requires only a cell voltage of ~1.54 V at 10 mA cm−2 current density, respectively. Extensive ab initio calculations were carried out to find out the overpotential for HER, orbital interaction through the determination of electron density of states and quantification of charge transfer by Bader charge analysis. The computed overpotential matched closely with the experimental data. The superior HER performance of the tri‐layer is enhanced due to the charge transfer (1.7444 e) to Fe‐doped Co‐LDH from Ni3S2‐MoS2 hybrid. This research strategy paves an effective pathway for affordable green H2 production and future efficient non‐precious bifunctional electrocatalyst design for overall water electrolysis. [ABSTRACT FROM AUTHOR]

Based on the first-principles density-functional theory, formation energies, transition energy levels of M (M = Mo, W) doped α-BiNbO4 systems are studied. The calculation results show that the donor defects form easily under Bi-rich condition. Of these, the Wint (W interstitial) and Moint (Mo interstitial) are the two main defects that lead to n-type conductivity. Then, the electronic structures of M-mono-doped and M/Ovac (O vacancy)-codoped α-BiNbO4 were investigated. Our results show that the band gap of Wint/Ovac-codoped α-BiNbO4 is reduced by 0.43 eV, and the conduction band minimum and valence band maximum are reduced by 0.20 and 0.23 eV, respectively, compared to pure α-BiNbO4, with less driving force required for the redox reaction process and then an increased redox rate. The α-BiNbO4 with Wint+Ovac defects with n-type conductivity has good photocatalytic activity in water splitting. [ABSTRACT FROM AUTHOR]

Heusler compounds and alloys represent a rapidly expanding family of materials that exhibit novel properties of significant interest for advanced technological applications. Electronic band structure calculations play a pivotal role in advancing research in this area. In an earlier study, we explored the properties of a new class of Heusler compounds based on Li, referred to as " p 0 -d semi-Heusler Compounds". In this study, we take the research a step further by focusing on " d 0 -d semi-Heusler Compounds", with the chemical formula KZ(Ga, Ge, As, or Se), where Z represents a transition metal. Our investigation centers on the structural, electronic, and magnetic properties of these compounds, particularly in relation to the three possible C 1 b structures. Most of these compounds are found to be magnetic and, notably, several among them exhibit half-metallicity making them appealing for applications in spintronics. Our findings provide a foundation for future experimental research on these materials. [ABSTRACT FROM AUTHOR]

Despite the fact that yttria-stabilized zirconia has been studied experimentally by optical and electron energy-loss spectroscopies, a first-principles theoretical interpretation of the dielectric response and electronic excitations is still lacking. The present study reports calculations of the complex dielectric function, reflectivity spectrum and electron energy-loss function of two ordered yttria–zirconia compounds: Zr6Y2O15 and Zr3Y4O12. The adopted methodology is based on linear-response theory with a semilocal density functional and the random-phase approximation including local-field effects. Comparisons with existing experimental data show an acceptable agreement showcasing how the different yttria content affects dielectric properties and spectra lineshapes. Strong discrepancies with experimental data are mainly confined to the low-energy part of the optical spectra and concern both the peak positions and the lineshape intensities. The onset of the optical absorption is considerably underestimated from the calculations owing to the well-known deficiency of semilocal density functionals to describe the quasiparticle band gaps. The energy-loss spectra, instead, are reproduced extremely well provided that local-field effects are included in the response functions. These effects are particularly important for the description of the semicore Zr–4p and Y–4p excitations, which dominate for higher energies (>30 eV) in the valence region. [ABSTRACT FROM AUTHOR]

All-d metallic Heusler compounds are promising materials for nanoelectronic applications. Such materials combining 3d, 4d, and 5d atoms have not yet been studied. In this respect, we perform ab initio electronic structure calculations and focus on Co 2 MnZ, Rh 2 MnZ, and Ru 2 MnZ compounds, where Z represents transition metal atoms from groups 3B, 4B, 5B, and 6B of the periodic table. Our results demonstrate that most of these compounds exhibit a distinctive region of very low minority-spin state density at the Fermi level when crystallized in the L 2 1 lattice structure. The Co-based compounds follow a Slater–Pauling behavior for their total spin magnetic moments, while the Ru-based compounds consistently deviate from the predicted Slater–Pauling values. Rh-based compounds show similarities to Co-based compounds for lighter Z atoms and to Ru-based compounds for heavier Z atoms. We find that the choice of the Z element within the same periodic table column has only a minor effect on the results, except for the Rh 2 Mn(Cr, Mo, W) compounds. Our findings suggest that these compounds hold significant promise for applications in spintronics and magnetoelectronics. [ABSTRACT FROM AUTHOR]

A trinuclear Co(II)-containing complex was assembled using the non-innocent hexahydroxytriphenylene bridging ligand. Cyclovoltammetry and spectroelectrochemistry studies revealed that the central ligand sustained four reversible redox events, leading to different species with diverse optical behavior. Complementary analysis of the molecular structure confirmed by ab initio theoretical calculations were consistent with the bridge in the tris-semiquinone (sq) state for the trinuclear complex. The exchange coupling among the electrons of the bridge resulted in a spin doublet (s = ½) localized close to one of the three Co2+ ions, as suggested by the experimental magnetic data. The central doublet underwent one large antiferromagnetic exchange coupling with one Co(II) and almost no coupling with the two other metal ions. [ABSTRACT FROM AUTHOR]

All-d metallic Heusler compounds are promising materials for nanoelectronic applications. Such materials combining 3d, 4d, and 5d atoms have not yet been studied. In this respect, we perform ab initio electronic structure calculations and focus on Co2MnZ, Rh2MnZ, and Ru2MnZ compounds, where Z represents transition metal atoms from groups 3B, 4B, 5B, and 6B of the periodic table. Our results demonstrate that most of these compounds exhibit a distinctive region of very low minority-spin state density at the Fermi level when crystallized in the L21 lattice structure. The Co-based compounds follow a Slater–Pauling behavior for their total spin magnetic moments, while the Ru-based compounds consistently deviate from the predicted Slater–Pauling values. Rh-based compounds show similarities to Co-based compounds for lighter Z atoms and to Ru-based compounds for heavier Z atoms. We find that the choice of the Z element within the same periodic table column has only a minor effect on the results, except for the Rh2Mn(Cr, Mo, W) compounds. Our findings suggest that these compounds hold significant promise for applications in spintronics and magnetoelectronics.

Using the density functional theory method, geometric optimization of layered polymorphic varieties of boron nitride, in which atoms are located in three different structural positions, was carried out and their energy and electronic properties were determined. The structures of the new polymorphs consist of boron and nitrogen atoms in a sp2-hybridized state and were modeled from hexagonal boron nitride by introducing topological defects 4-6-8, 4-6-10, 4-8-10, 4-16 and 4-6-12. As a result of the analysis, the possibility of the existence of nine new structural varieties was established. However, during the geometric optimization process, three structures turned out to be unstable, which were transformed into more stable polymorphic varieties BN-L4-8 and BN-L4-6-8. The layer density of the considered polymorphic varieties varies from 0.651 to 0.727 g/cm2.The sublimation energy values of the new structures range from 16,93 to 17,69 eV/(BN). The band gap varies from 3,20 to 4,03 eV. The relationships between the energy and structural parameters are determined.

Bonding interactions and spin-orbit coupling in the topological insulator SrAg4 Sb2 are investigated using DFT with orbital projection analysis. Ag-Ag delta bonding is a key ingredient in the topological insulating state because the 4dxy+4dx2-y2${4d_{xy} + 4d_{x^2 - y^2 } }$ delta antibonding band forms a band inversion with the 5 s sigma bonding band. Spin-orbit coupling is required to lift d orbital degeneracies and lower the antibonding band enough to create the band inversion. These bonding effects are enabled by a longer-than-covalent Ag-Ag distance in the crystal lattice, which might be a structural characteristic of other transition metal based topological insulators. A simplified model of the topological bands is constructed to capture the essence of the topological insulating state in a way that may be engineered in other materials.

At the air–water interface, many reactions are accelerated, sometimes by several orders of magnitude. This phenomenon has proved to be particularly important in water microdroplets, where the spontaneous oxidation of many species stable in bulk has been experimentally demonstrated. Different theories have been proposed to explain this finding, but it is currently believed that the role of interfacial electric fields is key. In this work, we have carried out a quantum chemistry study aimed at shedding some light on this question. We have studied two prototypical processes in which a hydroxide anion transfers its excess electron to either the water environment or a dioxygen molecule. To model the interface, we use a cluster of 21 water molecules immersed in an electric field, and we examine the energetics of the studied reactions as a function of field magnitude. Our results reveal that electric fields close to those estimated for the neat air–water interface (∼0.15 V ⋅ Å−1) have a moderate effect on the reaction energetics and that much stronger fields (>1 V ⋅ Å−1) are required to get spontaneous electron transfer. Therefore, the study suggests that additional factors such as an excess charge in microdroplets need to be considered for explaining the experimental observations. [ABSTRACT FROM AUTHOR]

The efficiency of catalysts relies on comprehending the underlying kinetics that govern their performance. Under the steady‐state regime, the "rate" is referred to as the turnover frequency, where the reaction rate is first order with respect to catalysts. Here, we introduce the Maximum Kinetic Efficiency (MaxKinEff) model, grounded in collision theory, to predict efficiency based on maximum turnover frequency, ΓmaxTOF0 ${{\rm{\Gamma }}_{max\;TOF}^0 }$ and maximum turnover number, τmaxTON0 ${\tau _{max\;TON}^0 }$. The model was applied to molecular water oxidation using twenty‐six transition metal catalysts from the first (3d), second (4d), and third (5d) rows. A thorough investigation reveals that [Ru(pda)(Br‐py)2] (pda=1,10‐phenanthroline‐2,9‐dicarboxylate; Py=pyridinophane) exhibits a notable ΓmaxTOF0 ${{\rm{\Gamma }}_{max\;TOF}^0 }$ of 1176.87×10−5 s−1 due to its larger collision diameter (σRC) and lower activation energy (Ea). Importantly, the trend in the computed τmaxTON0 ${\tau _{max\;TON}^0 }$ values aligns with experimental TON, τexperimentalTON0 ${\tau _{experimental\;TON}^0 }$ validating the model's accuracy. For instance, [Cp*Ir(κ2‐N,O)NO3] is identified by MaxKinEff as a standout performer, with the normalized maximum computed TON, τmaxTON0 ${\tau _{max\;TON}^0 }$ resembling the experimental TON, τexperimentalTON0 ${\tau _{experimental\;TON}^0 }$ =2000. [ABSTRACT FROM AUTHOR]

Despite the broadly acknowledged importance of solvation effects on measured UV/Vis spectra in the context of solvatochromism or chemical reactions in solution, it is still an open challenge to calculate UV/Vis spectra with predictive accuracy. This is particularly true when it comes to the impact of nuclear quantum effects on these experimental observables. In the present work, we calculate the UV/Vis absorption spectrum of indole in aqueous solution with a combination of a correlated wavefunction method for computing electronic excitation energies and enhanced path integral simulations for rigorous sampling of nuclear configurations including the quantum effects in solution. After validating our approach based on gas‐phase benchmarking, we demonstrate that the lineshape of the spectrum measured in aqueous solution is quantitatively recovered, without the application of any shifting, scaling, or broadening, only after including nuclear quantum effects in addition to thermal fluctuations and solvation at ambient conditions. Our findings demonstrate that nuclear quantum effects are “visible” in UV/Vis spectra of chromophores measured in solution even at room temperature and, therefore, that they must be considered computationally to achieve predictive accuracy. [ABSTRACT FROM AUTHOR]

New cobalt(II)‐based complexes with [N2O2] coordination formed by two bis‐chelate ligands were synthesized and characterized by a multi‐technique approach. The complexes possess an easy‐axis anisotropy (D<0) and magnetic measurements show a field‐induced slow relaxation of magnetization. The spin‐reversal barriers, i. e., the splitting of the two lowest Kramers doublets (UZFS), have been measured by THz‐EPR spectroscopy, which allows to distinguish the two crystallographically independent species present in one of the complexes. Based on these experimental UZFS energies together with those for related complexes reported in literature, it was possible to establish magneto‐structural correlations. UZFS linearly depends on the elongation parameter ϵT of the (pseudo‐)tetrahedral coordination, which is given by the ratio between the average obtuse and acute angles at the cobalt(II) ion, while UZFS was found to be virtually independent of the twist angle of the chelate planes. With increasing deviation from the orthogonality of the latter, the rhombicity (|E/D|) increases. [ABSTRACT FROM AUTHOR]

Quantum information theory provides a powerful toolbox of descriptors that characterize many‐electron systems based on quantum information patterns between open quantum systems. Despite the wealth of insights gained in the condensed matter community, the use of these descriptors to study interactions between atoms in a molecule remains limited. In this study, we develop a quantum information framework for molecules that characterizes the quantum information patterns between quantum atoms as defined in the Quantum Theory of Atoms in Molecules. We show that quantum information analyses capture key properties of quantum atoms and how they interact with their molecular environment. Additionally, we show that the presence of bond critical points can remain invariant despite large changes in the quantum information patterns between the quantum atoms. Our findings indicate that quantum information theory can shed a new light on molecular electronic structure. [ABSTRACT FROM AUTHOR]

AbstractUranium-zirconium (U-Zr) alloy fuels have been taken into consideration for fast reactors because of their superior reactor safety, high uranium (U) density, and excellent thermal conductivity. In this paper, the structural and mechanical properties of metallic U and U-Zr alloy fuels are calculated at the atomic level by density functional theory–based calculations with Hubbard U (density functional theory + U) corrections. Several structure-property relations, such as lattice volume, bulk modulus, Young’s modulus, shear modulus, electronic density of states, etc. are calculated for U metal and U-Zr alloy fuels. In addition, the Zr content in metallic U fuel is adjusted from roughly 5 at. % to 15 at. % in order to determine how the Zr content affects the characteristics of U-Zr fuel material. A linear relationship between the volume and Zr concentrations is observed. The concentration of Zr in the fuel affects the mechanical characteristics of U-Zr alloy fuel. It is also observed that the electronic structure of the α-U phase is not changed significantly in the presence of Zr. Our computations provide insight into how U-Zr alloy fuels behave in reactor conditions. [ABSTRACT FROM AUTHOR]

2,5‐bis(hydroxymethyl)furan (BHMF) derived from 5‐Hydroxymethylfurfural (HMF) through a hydrogenation process has extensive applications in the production of resins, polymers, and artificial fibers. However, screening out the candidate and then modulating the active site to optimize the catalyst for high yield of BHMF are currently insufficient. In this study, Gibbs free energy diagrams of the reduction of HMF on 13 metals were presented, along with the identification of the rate‐determining step (RDS) with the highest reaction barrier for each metal. We attempted to construct a volcano plot for HMFRR reaction. Additionally, a strategy was proposed to adjust the reaction barriers of RDS by combining two appropriate metals. Further experiments confirmed that Pb with the lowest energy barrier exhibited the highest HMF conversion (BHMF selectivity) among single metals. The modified catalyst by doping Ag on Pb, further boosted the HMF conversion (BHMF selectivity) from 42.1 % (59.4 %) to 80.8 % (80.9 %), respectively. These results provide an approach to rationally design and construct the catalyst system for efficient conversion of HMF. [ABSTRACT FROM AUTHOR]

The current investigation employs first‐principles DFT (density functional theory) calculations to examine the influence of transition metal replacements on the structural, thermodynamic, and thermoelectric properties of Cu‐based chalcogenides TMCu3Se4 (TM = Nb/Ta/V). The PBE‐generalized gradient approximation (GGA) model is utilized to compute the fundamental properties of Cu‐based chalcogenides under study. A thorough examination of the energy band structures indicates that these chalcogenides are semiconductor compounds with indirect energy bandgaps. We can infer from the calculated energy band structures that the bandgap values are 1.67, 1.77, and 1.05 eV for NbCu3Se4, TaCu3Se4, and VCu3Se4, respectively. The ZTe$$ {\mathrm{ZT}}_e $$ values for NbCu3Se4, TaCu3Se4, and VCu3Se4 are 0.661, 0.998, and 0.996, respectively. These values make them highly appropriate for usage in thermoelectric (TE) devices. The thermoelectric characteristics of pyrochlore oxides TMCu3Se4 (TM = Nb/Ta/V) suggest that these materials have promising potential for energy‐related applications. The analyzed thermodynamic properties demonstrate that the Cu0based chalcogenide materials TMCu3Se4 (TM = Nb/Ta/V) exhibit a notable level of thermal stability. [ABSTRACT FROM AUTHOR]

The collisions between Na atoms and H2 molecules are of great significance in the field of chemical reaction dynamics, but the corresponding dynamics results of ground-state reactions have not been reported experimentally or theoretically. Herein, a global and high-precision potential energy surface (PES) of NaH2 (12A′) is constructed by the neural network model based on 21,873 high-level ab initio points. On the newly constructed PES, the quantum dynamics calculations on the Na(2S) + H2(v0 = 0, j0 = 0) → NaH + H reaction are carried out using the time-dependent wave packet method to study the microscopic reaction mechanism at the state-to-state level. The calculated results show that the low-vibrational products are mainly formed by the dissociation of the triatomic complex; whereas, the direct reaction process dominates the generation of the products with high-vibrational states. The reaction generally follows the direct H-abstraction process, and there is also the short-lived complex-forming mechanism that occurs when the collision energy exceeds the reaction threshold slightly. The PES could be used to further study the stereodynamics effects of isotope substitution and rovibrational excitations on the title reaction, and the presented dynamics data would provide an important reference on the corresponding experimental research at a higher level. [ABSTRACT FROM AUTHOR]

This article reports the synthesis, along with structural and photophysical characterization of 2‐(2'‐hydroxyphenyl)benzazole derivatives functionalized with various azaheterocycles (pyridine, pyrimidine, terpyridine). These compounds show dual‐state emission properties, that is intense fluorescence both in solution and in the solid‐state with a range of fluorescent color going from blue to orange. Moreover, the nature of their excited state can be tuned by the presence of external stimuli such as protons or metal cations. In the absence of stimuli, these dyes show emission stemming from anionic species obtained after deprotonation (D* transition), whereas upon protonation or metal chelation, ESIPT process occurs leading to a stabilized and highly emissive K* transition. With the help of extensive ab initio calculations, we confirm that external stimuli can switch the nature of the transitions, making this series of dyes attractive candidates for the development of stimuli‐responsive fluorescent ratiometric probes. [ABSTRACT FROM AUTHOR]