Entropy-driven dual-phase engineering in sulfides via synergizing metallic conduction and disorder-interface polarization for microwave absorption.

Advance sensing of high energy explosive: A DFT-Based study of C5N framework performance.

A conspicuous ternary hydride Fm3̄m-LaBeH8 superconductor with a particular Be-H alloy backbone was initially predicted in theory and subsequently synthesized experimentally with the measured superconducting critical temperature Tc of 110 K under the moderate pressure of 80 GPa. Previous investigations mainly aimed at deciphering its structural characteristics and superconductivity. Few explorations involved other physical and chemical properties, which are invaluable for its practical application. Herein, on the basis of the first-principles calculation, we comprehensively investigate the structural, bonding, mechanical, electronic, superconductive, thermophysical and optical properties for the cubic Fmm-LaBeH8 structure under various pressures ranging from 20 to 120 GPa. The bonding essence in Fm3̄m-LaBeH8 is theoretically predicted as the ionic La-H bond and the synthetic Be-H bond with the ionic and covalent characters, respectively. Moreover, the Fm3̄m-LaBeH8 crystal is predicted to be thermodynamically, mechanically and dynamically stable within the considered pressures. A linear increase with the increasing pressure in elastic constants (C11 and C12) and bulk modulus B is achieved. More interestingly, the shear modulus G and Young's modulus E undergo a distinct and complicated variation process upon further compression, similar to those of the elastic constant C44, transverse and mean sound velocities, Vickers hardness Hv and Debye temperature θD. The remarkable superconductivity originates from the high hydrogen-dominated electronic density of states around the Fermi energy and the overriding hydrogen contribution to the electron-phonon coupling strength. Notably, the high superconducting critical temperature Tc in the Fm3̄m-LaBeH8 configuration stems from the combined effect of λ and ωlog. In addition, Fm3̄m-LaBeH8 is an underlying absorbing material for the visible and UV light regions. These findings increase the understanding of the excellent superconductivity and the remaining physical properties of the LaBeH8 superconductor, greatly stimulating enthusiasm for its synthesis for experimental researchers and broadening its practical applications.

Bismuth oxyhalides (BiOX, X = Cl, Br, and I) are promising photocatalytic materials whose electronic and optical properties can be systematically tuned through halogen alloying. This study presents a comprehensive computational and experimental investigation of halogen anion alloying effects on the electronic structure and optical properties of BiOCl1-xBrx, BiOCl1-xIx, and BiOBr1-xIx alloy systems. Using density functional theory calculations combined with the generalized quasichemical approximation, we systematically investigated band gaps and density of states for all symmetrically non-equivalent configurations in 24-atom supercells. Our calculations reveal significant band gap bowing behavior with bowing parameters of 0.98, 2.23, and 2.70 eV for BiOCl1-xBrx, BiOBr1-xIx, and BiOCl1-xIx alloys, respectively, representing substantial deviations from Vegard's law. Point defect formation energy calculations demonstrate that although halogen substitution is endothermic, the formation energies remain sufficiently low (2-143 meV per dopant atom) to enable experimental synthesis. The mixing enthalpies remain below 10 meV per formula unit across the entire composition range for all three systems. At typical synthesis temperatures, the configurational entropy contribution easily overcomes the enthalpy penalty, stabilizing the random solid solution. We successfully synthesized BiOCl1-xIx nanoparticles across the complete composition range (x = 0-1) with yields exceeding 90%, experimentally validating our predictions. UV-visible spectroscopy of the synthesized alloys confirms the predicted red-shift in absorption onset with increasing iodine content. While the electronic band structures exhibit strong bowing effects, the absorption spectra are reasonably captured by a linear interpolation between pure end-members, providing a practical approximation for targeted optical design applications. The minimum band gaps occur at approximately 75-78% heavier halogen content, offering optimal visible light absorption. These findings provide fundamental insights into halogen alloying mechanisms in bismuth oxyhalides and establish clear design principles for enhanced photo-absorption or photo-catalytic applications.

The possibility of using 2D bilayer silicon carbide (SiC) as a sensor for alcohol molecules (ethanol, methanol, and acetone) has been proposed and analyzed. Pristine 2D SiC bilayer is an indirect band gap semiconductor with a band gap of 2.62eV. After adsorption of ethanol, methanol, and acetone, the material exhibits a transition to a direct band gap with values of 1.72eV, 2.72eV, and 1.70eV, respectively. The modifications observed in the energy band gap, total density of states (TDOS), partial density of states (PDOS), and optical properties indicate that the 2D SiC bilayer is highly sensitive to ethanol and acetone adsorption. These findings suggest strong feasibility of 2D SiC bilayer as an effective alcohol sensor, in good agreement with previously reported theoretical and experimental studies. The sensing performance of 2D SiC bilayer toward ethanol, methanol, and acetone was investigated through the CASTEP package in Material Studio simulation software. Key parameters including band structure, band gap variation, total density of states (TDOS), partial density of states (PDOS), and optical characteristics were evaluated to determine sensitivity and adsorption effects. The results were compared with previously reported theoretical and experimental data to validate the findings.

We investigate effects of the density of states of condensed matter on the electronic excitations triggered by penetrating keV ions, in a systematic study of energy deposition along multiple well-defined channeling trajectories. We measure the specific energy deposition of ions with keV energies transmitted through Si-a band gap material-in the form of single-crystalline, self-supporting membranes. Energy transfers observed for Ne ions along the 〈100〉, 〈211〉, and 〈111〉 channeling orientations agree well in magnitude with predictions from density functional theory for the expected unperturbed electron densities in an electron gas. This agreement indicates that, along channeling trajectories, the interaction is dominated by conduction and valence electrons, with atomic (core-electron) processes largely suppressed. In contrast, for H and He ions, the predicted values are found systematically higher than the measured values. Non-linearities in the energy dependence of the specific energy deposition of Ne ions are found along all studied low-index orientations, with an inverted behavior observable for random in comparison to channeling orientation. In this context, we discuss the experimental challenges of limiting selected trajectories for the lowest velocities studied, which can mask effects of electronic excitation thresholds in the target electronic system. The new insights shed also light on earlier studies reporting a complex scaling of energy deposition with excitation thresholds, or even their apparent absence.

In this study, a comparative quantum-chemical investigation of 2-chloro-N-(4-methoxyphenyl)acetamide (p-acetamide), 2-(4-methoxyphenylamino)-2-oxoethyl acrylate (MPAEA),and 2-(4-methoxyphenylamino)-2-oxoethyl methacrylate (MPAEMA) was carried out to elucidate the effects of progressive structural modification on their electronic, spectroscopic, thermochemical, and non-covalent interaction properties. Geometry optimizations and electronic-structure calculations were performed within the framework of density functional theory using the 6-311G basis set. Electronic properties were analyzed through natural bond orbital (NBO) analysis, frontier molecular orbital (FMO) distributions, and global reactivity descriptors. The calculated HOMO-LUMO energy gaps revealed that MPAEA exhibits enhanced charge-transfer capability because of its conjugated acrylate structure, whereas MPAEMA shows a larger gap, suggesting higher electronic stability. Time-dependent density functional theory (TD-DFT) calculations were used to predict UV-Vis absorption features, revealing that structural modification significantly influences excitation energies and optical responses. Molecular electrostatic potential (MEP) maps and density of states (DOS/tDOS) analyses provided further insight into charge distribution and orbital contributions, highlighting increased electron delocalization in conjugated systems. Thermochemical analysis showed that thermal energy, heat capacity, and entropy increased systematically with temperature for all molecules, with MPAEMA exhibiting the highest thermodynamic values because of its extended molecular framework. Non-covalent interaction (NCI), density overlap regions indicator (DORI), and reduced density gradient (RDG) analyses revealed distinct weak-interaction patterns, confirming that structural complexity enhances interaction diversity and electron-density distribution. Overall, the results indicate that the transformation from the acetamide framework to acrylate and methacrylate derivatives significantly modifies the electronic structure, optical behavior, thermodynamic response, and interaction topology of methoxyphenyl-based molecular systems.

Chiral quasi-bound states in the continuum (q-BICs) have recently emerged in metaphotonics as resonances that combine ultra-high-quality factors with near-unity circular polarization in the far field. However, these states are typically confined to the Γ-point (normal incidence) due to their symmetry-protected origins. We propose a new mechanism for realizing light-cone-proximal chiral q-BICs at large oblique angles, enabled by the divergence of the radiative density of states near the light cone. Using dielectric metasurfaces with a monoclinic lattice and broken in-plane mirror symmetry, we demonstrate that tuning the lattice angle allows for robust control of these resonances. The resulting chiral q-BICs exhibit near-unity circular dichroism in transmission and fully circularly polarized emission at angles exceeding 50° from normal. Our results establish a general route to off-normal and grazing-angle chiral q-BICs, enabling directional chiral lasing and providing a versatile platform for quantum and nonlinear photonics.

We investigate machine-learned force fields (MLFFs) trained on approximate density functional theory (DFT) and coupled cluster (CC) level potential energy surfaces for the carbon diamond and lithium hydride solids. We assess the accuracy and precision of the MLFFs by calculating phonon dispersions and vibrational densities of states (VDOS) that are compared to experimental and reference ab initio results. To overcome limitations from long-range effects and the lack of atomic forces in the CC training data, a delta-learning approach based on the difference between CC and DFT results, as well as a charge-aware MLFF approach, is explored. Compared to DFT, MLFFs trained on CC theory yield higher vibrational frequencies for optical modes, agreeing better with the experiment. Furthermore, the MLFFs are used to estimate anharmonic effects on the VDOS of lithium hydride at the level of the CC theory.

Two-dimensional (2D) ferroelectric (FE) materials offer unique opportunities for molecular sensing because their switchable polarization strongly couples surface chemistry with electronic response. Here, we use first-principles calculations to investigate the adsorption of representative organic molecules on monolayer CuInP2S6 (CIPS) and demonstrate how molecular interactions modulate FE polarization and near-surface electronic structure in monolayer CIPS. All investigated molecules exhibit thermodynamically favorable adsorption, revealing a robust molecule-surface interaction across diverse chemical functionalities. Adsorption-induced coordination, particularly through O-Cu and N-Cu interactions, drives local Cu displacement and breaks the intrinsic symmetry between FE states, generating pronounced molecule-dependent FE energy asymmetry of up to 282 meV together with out-of-plane polarization asymmetry reaching 0.54 μC/cm2, as confirmed by Berry-phase polarization calculations. This asymmetry persists in the presence of a static interfacial water layer, indicating that adsorption-polarization coupling remains effective under realistic environmental conditions. In all investigated systems, the adsorption complexes remain semiconducting, indicating that molecular adsorption does not suppress the intrinsic semiconducting character of monolayer CIPS. Electronic structure analysis reveals FE-state-dependent electronic asymmetry and characteristic projected density of states (PDOS) signatures arising from Cu-molecule hybridization, providing experimentally accessible spectroscopic fingerprints. Relative energetics of representative Cu-displacement configurations suggest that polarization evolution proceeds through intermediate ferrielectric (FiE) and antiferroelectric-like (AFE-like) states without requiring a paraelectric (PE) intermediate, even under molecular adsorption. These results demonstrate that molecular adsorption can serve as an effective route for tuning ferroelectric polarization and near-surface electronic structure in 2D ferroic materials. Based on these findings, we propose a monolayer CIPS-based ferroelectric field-effect transistor (FET) architecture in which adsorption-induced polarization asymmetry may influence the local electronic response of the CIPS channel. This work establishes an atomistic framework for understanding adsorption-induced polarization asymmetry in 2D ferroelectrics and suggests potential implications for future ferroelectric sensing architectures.

Non-radiative voltage loss (ΔVnr) is a major factor limiting the efficiency of organic solar cells (OSCs), yet its microscopic origin remains unclear due to the complex morphology of bulk heterojunction photoactive layers. In this work, we design a triple-layer device configuration that controls the density of donor/acceptor (D/A) interfaces without changing the composition or thickness of the photoactive layer. This strategy decouples interfacial characteristics, material parameters, and device performance, allowing us to direct probe their intrinsic relationships. We find that ΔVnr originates not only from carrier lifetime effects but also from thermodynamic redistribution between locally excited (LE) and charge-transfer (CT) states. Increasing the density of D/A interfaces broadens the excitonic density of states, reduces the activation energy for LE-to-CT conversion, and enhances recombination via non-radiative CT channels. Strong correlations among Urbach energy (EU), activation energy, and ΔVnr highlight their critical role in governing voltage losses in OSCs. Our results clarify the microscopic mechanisms behind non-radiative losses and offer a general design strategy to suppress ΔVnr in next-generation OSCs.

The reliable detection of toxic and greenhouse gases is essential for environmental monitoring, industrial safety, and public health protection. In this work, a comprehensive first-principles density functional theory study was carried out to investigate the adsorption and gas-sensing performance of a ZnO-decorated WSe2 monolayer toward CO2, N2O, CH4, SF6, CCl2O and CH3Cl gases. The results show that pristine WSe2 exhibits weak adsorption due to limited gas-surface interaction, whereas ZnO decoration significantly enhances the adsorption behavior by increasing adsorption energies, reducing adsorption distances, and promoting charge transfer. Among the investigated gases, the ZnO-WSe2 system exhibits the strongest interaction toward CCl2O and CH4, with adsorption energies of -0.566 eV and -0.542 eV, respectively. Electronic structure analysis, including band structure, density of states, differential charge density, and work function calculations, reveals pronounced gas-dependent electronic responses and confirms strong modulation of the electronic properties after gas adsorption. Sensitivity analysis indicates that the ZnO-WSe2 monolayer exhibits excellent sensing performance, particularly toward CCl2O, with appreciable responses also observed for CO2 and CH4, while recovery time calculations demonstrate that the desorption behavior can be effectively tuned by temperature. Furthermore, the strong binding interaction between ZnO and WSe2 confirms the structural stability of the decorated monolayer under practical sensing conditions. These findings demonstrate that ZnO decoration is an effective strategy for activating the WSe2 surface and improving its gas-sensing performance, highlighting ZnO-WSe2 as a promising and selective sensing material for toxic gas detection and providing valuable theoretical guidance for the design of high-performance two-dimensional gas sensors.

A gated integrating laser-combined scanning tunneling microscope has been developed for high-fidelity investigation of photophysical processes at the atomic scale. This instrument integrates a low-repetition-rate, high-pulse-energy laser with a synchronized gated-integration scheme, enabling selective extraction of the laser-induced tunneling current. To demonstrate its performance, atomically resolved topography and surface photovoltage mapping were simultaneously obtained on the Si(111)-(7 × 7) surface. The surface photovoltage distribution is found to be strongly correlated with the underlying atomic structure. In addition, a highly localized enhancement of the laser-induced tunneling current is observed at a specific single-atom defect site. Detailed analysis, supported by local density of states measurements, reveals that this defect possesses an unusually high density of deep valence-band states. This distinctive electronic structure likely promotes Auger recombination between photogenerated holes accumulated under positive sample bias and electrons tunneling from the tip, thereby giving rise to the observed increase in the local tunneling current.

Cubic boron nitride (c-BN) is a promising catalyst or catalyst substrate with good thermal, chemical, and mechanical stability. However, the large bandgap (Eg) limits its photocatalytic activity under visible light, but it is able to work in the UV region or can be used as a composite with other narrow Eg semiconductors. In this theoretical study, we investigate the structural, electronic, optical, and thermodynamic properties of c-BN nanoparticles using density functional theory (DFT) calculations within the CASTEP and Dmol3 frameworks. The computed Raman, FTIR, and XRD spectra confirm a cubic zinc-blende-like structure of c-BN. Electronic structure calculations using generalized gradient approximations (GGA), B3LYP, and HSE06 functionals show a direct bandgap of 4.533 eV (GGA/PBE), 4.381 eV (B3LYP), and 4.507 eV (HSE06), consistent with UV-limited absorption, and illustrate its limited visible-light absorption. Density of states and electron localization function analyses highlight the polar covalent B─N bonding and charge distribution, revealing that boron p-orbital states are dominant in the conduction band (CB) while nitrogen p-orbital states are mostly available in the valance band (VB), and this inequality of state distribution makes B atoms good electron acceptors and N atoms good donors during the catalysis process. Thermodynamic properties also indicate thermal stability and suitability for high-temperature catalysis. Phonon dispersion analysis also confirms dynamical stability, with no imaginary frequencies. Optical property analysis shows a broad and intense absorption peak, high dielectric response, and low reflectivity, which suggests a favorable electron-hole separation. A wide band edge alignment of c-BN relative to water redox potentials suggests that c-BN can drive the generation of reactive oxygen species, which support its potential in photocatalysis, such as water splitting and pollutant degradation.

Deciphering the ESIPT mechanism and AIE behavior of HNBT under controlled polarity gradients: A theoretical study.

Twisted bilayer kagome (TBK) lattices provide a tunable moiré platform for realizing higher-order topological (HOT) phases in two dimensions. In this study, we employ tight-binding modelling together with Wilson-loop and nested Wilson-loop analyses to investigate the topological properties of the TBK system. The calculated band structure exhibits a finite bulk gap, within which the Wilson spectra reveal a quantized quadrupole moment Qxy = 1/3, corresponding to fractional corner charges Q∞c ≈ -0.31e. Finite-size scaling confirms the thermodynamic stability of these fractionalized charges, while local density of states (LDOS) spectra and real-space maps visualize sharply localized zero-energy corner modes. Under an applied magnetic flux, the corner states exhibit a continuous spectral flow across the bulk gap, demonstrating higher-order topological pumping. These results establish twisted kagome bilayers as a controllable moiré platform for realizing higher-order topology and suggest experimentally accessible signatures for detecting quantized corner states in kagome-based van der Waals heterostructures.

Herein, we demonstrate how Fermi-level pinning at buried contacts impacts solar fuel generation in all-polymer photocathodes by systematically comparing the effects of work function, hydroxyl coverage, and hydrogen evolution using chemically modified indium tin oxide (ITO) supports. Photovoltages and net photocathode performance are improved when the ITO is passivated using phosphonic acids, independent of work function, suggesting that the passivation reduces Fermi-level pinning at the buried interface arising from blended heterojunction interactions with surface metal hydroxyls. Transient photovoltage decay reveals differences in recombination mechanisms, supported by light intensity-dependent measurements. Briefly, nonpassivated, hydrophilic contacts exhibit trap-assisted recombination, while passivated, hydrophobic contacts follow bimolecular recombination. We then investigate changes in electroactivity of hole-transfer processes as a function of scan rate and repetitive cycling using a diffusion-controlled molecular redox probe, analogous to a hole-only device achieved via the electrolyte. The nonpassivated buried contacts exhibit higher overpotentials for oxidation, indicative of hole injection/extraction barriers. We observe irreversible electron transfer via the hole-transport level of the blended heterojunction and a strong cycle dependence, consistent with changes in the hole trap state density. Passivation results in more reversible redox behaviors, consistent with more Ohmic-like contacts. Collectively, these results provide context toward the realization of durable organic photoelectrodes with optimized photovoltages and net solar-to-hydrogen conversion efficiencies via fundamental understanding of the rates of carrier generation, recombination, and transport in high-dielectric aqueous environments and opportunities to characterize buried interfaces under device-relevant electric fields.

Silicon-based optoelectronic devices represent a cornerstone of modern optoelectronics, owing to their low cost and mature fabrication infrastructure. Their performance optimization hinges critically on precise control of the Schottky barrier height (SBH). As a nondestructive, continuously tunable physical parameter, pressure offers a novel strategy for dynamic SBH modulation. Here, we employed high-pressure techniques to investigate Pt/Si Schottky junctions. With increasing pressure, the SBH decreased monotonically from 0.713 to 0.446 eV at a rate of -165.8 meV/GPa and was completely eliminated above 4.3 GPa, indicating a pressure-driven Schottky-to-Ohmic transition. Mechanistic analysis revealed that pressure modulates SBH primarily by regulating interfacial gap state density and reconstructing the band structure. This transition led to a drastically enhanced photoresponse, with photocurrent intensities increasing by 100-fold and 3400-fold under 532 and 660 nm laser excitation, respectively. This work elucidates the pressure-tuning behavior of silicon-based Schottky junctions and their regulatory mechanism on photoelectric performance, providing a new strategy for the design of high-performance silicon optoelectronic devices.

In this study, we propose an integrated approach to extract the intrinsic oxide trap density (Not,int) in amorphous indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs) by combining low-frequency noise (LFN) measurements with sub-bandgap optical excitation. As the channel thickness (Tch) is scaled down from 30 to 3 nm, a pronounced increase in 1/f noise is observed, accompanied by an enhanced subgap density of states (DOS) and increased Coulomb scattering arising from trap-limited conduction. Our results show that the elevated power spectral density (PSD), originating from bulk defect-induced carrier trapping and detrapping, can lead to a significant overestimation of oxide trap density (Not) when conventional LFN analysis is applied. To address this issue, we introduce a compensated volume factor (Vf) based on sub-bandgap optical illumination (λ = 450 nm, Eph = 2.75 eV) for suppressing bulk trap contributions and accounts for the effective conduction channel within the Debye screening length (LD). Specifically, the extracted Not were corrected from 2.1 × 1019 eV-1 cm-3, 1.2 × 1020 eV-1 cm-3, and 3.1 × 1020 eV-1 cm-3 to 1.4 × 1019 eV-1 cm-3, 1.3 × 1019 eV-1 cm-3, and 1.3 × 1019 eV-1 cm-3, for 30, 10, and 3 nm devices, respectively, indicating trap distribution within an equivalent gate-oxide depth of approximately 1.4 nm-1.9 nm from the interface. Therefore, this methodology enables the separation of interface-related trapping effects from bulk noise contributions and provides a quantitative framework for identifying the intrinsic spatial distribution of oxide traps, thereby facilitating further gate stack and interface optimization in scaled devices. The proposed approach, considering the bandgap properties of the material, can be extendable for broad applicability across oxide semiconductor systems and device structures, offering a useful framework for performance and reliability enhancement in advanced TFT technologies.

The structural, thermal, electrical transport, and magnetic properties of ternary compounds BaT2P2(T=Ru, Pd) are reported together with electronic structure calculations. Our results show that BaRu2P2crystallises in the layered tetragonal ThCr2Si2-type structure (space groupI4/mmm) whereas BaPd2P2adopts the primitive tetragonal CeMg2Si2-type structure (space groupP4/mmm). The combined experimental results and electronic structure calculations suggest metallic and diamagnetic ground states for both materials. Electrical transport measurements further indicate non-Fermi liquid behaviour at low temperatures. Notably, BaRu2P2exhibits an anomalous feature in the magnetic susceptibility atT∼260K, similar to that observed in BaRu2As2. A comparison between the bare density of states obtained from electronic structure calculations and the experimentally estimated values suggests the presence of strong correlation effects in the material. Furthermore, the heat capacity of BaPd2P2, calculated using the full phonon dispersion relation, is in good agreement with the experimental data, particularly at low temperatures, highlighting the significant contribution of optical phonon branches toCpin this temperature range.