Thiosaccharinate-bridged triosmium clusters containing a pnictogen donor ligand: Synthesis, structure, isomerism and electronic structure calculations

Spin oriented calculation of electronic band structure, thermoelectric, optical, and vibrational properties of ScGa2Ru Heusler alloy: DFT approach

Structural elucidation and thermal behavior of l-tyrosine hydroiodide: Hirshfeld surface analysis, halogen-dependent stability, and vibrational dynamics.

OH-initiated oxidation of N-methyl-2-pyrrolidone: Kinetics, environmental fate, and implications for biological interactions.

Amorphous/crystalline interfaces that combine structural distortion with local charge redistribution remain poorly understood, mainly owing to limited access to atomically well-defined single-crystalline components and correlative probes of interfacial fields. Herein, we construct atomically resolvable single-crystalline/amorphous heterointerfaces by synthesizing a library of transition metal oxytellurides and map the projected electric field and strain by combining scanning transmission electron microscopy (STEM) with four-dimensional STEM (4D-STEM). In RuTe1.93O0.97, 4D-STEM reveals a locally enhanced electrostatic field whose direction reorients at the interface. Charge density maps show electron accumulation in the amorphous region and depletion in the single-crystalline region, suggesting directional electron transfer. Nanometer-scale tensile and compressive strain localized around the heterointerface is identified. Electronic structure calculations indicate enhanced Ru 4d delocalization near the Fermi level, facilitating electron-driven reactions. This work spatially correlates atomic structure with built-in electric fields and lattice strain at disordered-ordered interfaces, providing a general route to elucidating structure-activity relationships.

Pyrolysis is an important thermochemical conversion process for biomass and is conducted in the absence of oxygen at temperatures between 400 and 1000 ∘C. Biomass pyrolysis yields cleaner combustion fuels by decreasing fuel-bound oxygen and nitrogen species, thus reducing NOX formation and net CO2 emissions. A structural model compound for cyclic peptides — important nitrogen-containing components in biomass — is 2,5-diketopiperazine (DKP). In this work, we apply an automated workflow that combines reactive molecular dynamics simulations with electronic structure calculations at different levels of theory to develop a detailed kinetic model for the pyrolysis of DKP at the level of elementary reaction steps. This complements previous studies that focused only on the net reaction scheme. The developed DKP kinetic submodel for pyrolysis is implemented in the kinetic modeling software OpenSMOKE++ . Under pyrolysis, DKP decomposes into hydrogen cyanide (HCN), carbon monoxide (CO) and hydrogen (H2). Ammonia (NH3) is not formed in primary decomposition steps but rather in secondary reactions involving the primary intermediates. The submodel qualitatively reproduces DKP pyrolysis products observed in a fluidized bed reactor under kinetically controlled conditions and provides a reliable basis for further studies on peptide decomposition. Beyond the specific kinetic submodel, this work proposes a general workflow for investigating thermal decomposition and combustion processes.

Unambiguous Polaron and bipolaron localization in the novel conducting polymer poly(durentetraoxidithiophene) (PDTODT) through electronic structure calculations.

Raman spectroscopy has become a powerful tool for studying material properties due to its precise identification of structural features. Previous studies have focused more on the qualitative changes indicated by Raman peaks, with little attention paid to the quantitative changes indicated by Raman intensity. Based on the theoretical calculations of Raman spectra and electronic structures of a series of semiconductors under different pressures, and through further statistical analysis, we established a relationship between Raman intensity and band gap in the form of a formula. When Raman intensity increases, it is always accompanied by a decrease in the band gap. These insights provide a broader perspective for the applications of Raman spectroscopy.

First-principles insights into the structural, optoelectronic, and thermoelectric properties of lead-free halide double perovskites Rb2AlAgX6 (X = Cl, Br, I) for energy applications.

The potential energy surface (PES) of the Cl(2P3/2) + C2H5I reaction is described by highly-accurate electronic structure computations, covering both hydrogen- and iodine-abstraction pathways and several substitution routes proceeding through either Walden inversion or front-side attack, including both atom- (H, I) and group-exchange (CH2I, CH3) mechanisms. Geometries and harmonic vibrational frequencies of all stationary points are determined at the MP2/aug-cc-pVDZ and CCSD(T)-F12b/aug-cc-pVDZ levels of theory, and single-point energies are further refined at the most accurate geometries using the coupled-cluster method with aug-cc-pVTZ and aug-cc-pVQZ basis sets. To target chemical accuracy, five additional energy corrections - accounting for core correlation, scalar relativistic, spin-orbit, and post-CCSD(T) effects - are incorporated into the CCSD(T)-F12b/aug-cc-pVQZ single-point energies. The resulting benchmark data allow for the detailed mapping of the reaction pathways, including the identification of transition states and pre- and post-reaction minima, which guide the system from the reactants toward the various product channels on the PES. Rate coefficients are determined using transition-state theory, including the Wigner tunneling correction, and compared to literature theoretical values.

Alloy-type anodes offer high capacity, but deep lithiation usually causes severe volume expansion and structural instability. Identifying a thermodynamically stable intermediate phase with a moderate lithiation potential may offer a viable route to mitigating this dilemma. Here, we propose a hierarchical computational workflow that combines global structure search with a machine-learning interatomic potential to systematically explore phase evolution in the Li-rich region of the Li-As binary system. Fine-tuning a pretrained potential on a dataset of approximately 3500 configurations labeled by density functional theory (DFT) yields an energy root-mean-square error (RMSE) of 25.3 meV per atom on an independent test set. Structure screening with the fine-tuned potential, followed by DFT validation, reveals a thermodynamically stable intermediate phase, C2/c-Li3As2, lying on the convex hull between LiAs and Li3As. Phonon and electronic-structure calculations show that this phase is dynamically stable at 0 K and metallic. Electrochemical thermodynamic analysis indicates an equilibrium potential of about 0.95 V (vs. Li/Li+) for the LiAs ⇌ Li3As2 two-phase reaction. When lithiation is limited to Li3As2, the theoretical capacity reaches 536.6 mAh g-1 with a volume expansion of about 68.6%. Further climbing-image nudged elastic band (CI-NEB) calculations and molecular dynamics (MD) simulations show a low Li+ migration barrier. These results identify C2/c-Li3As2 as a promising intermediate phase for shallow-lithiation strategies and highlight its potential for fast-charging anodes.

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.

Understanding how the introduction of functional groups influences the interaction between metal-organic frameworks and small organic molecules is essential for designing materials capable of mitigating the effects of psychoactive substances. In this study, a set of UiO-66-type zirconium frameworks modified with distinct linker substituents was examined to determine how these variations alter their response toward mephedrone (4-MMC). The selected functional groups introduced changes in polarity and acidity that significantly affected the behaviour of the materials in media of different composition. The framework bearing a sulfonic acid group rapidly removed nearly all detectable 4-MMC from aqueous solution, whereas derivatives containing amino-based functionalities performed more effectively under conditions resembling physiological fluids. These findings emphasise the combined influence of linker chemistry and medium composition on the uptake process. Electronic-structure calculations were used to gain deeper insight into the origin of these trends. The analysis showed that frameworks containing sulphur-based substituents form particularly stable host-guest configurations through cooperative contributions from dispersive, electrostatic, and partially covalent interactions. Aromatic stacking interactions were present but contributed less significantly than charge-related interactions. Biological evaluation confirmed that the modified frameworks exhibit minimal intrinsic toxicity and can attenuate several harmful effects produced by 4-MMC in both cell models and zebrafish larvae. Among the studied materials, the amino-functionalized derivative provided the clearest protective effect, reducing behavioural disturbances and developmental abnormalities triggered by the drug. This work demonstrates that rational modification of UiO-66 linkers offers an effective route to control the bioavailable fraction of 4-MMC, highlighting the potential of such materials for future detoxification strategies involving synthetic cathinones.

We present a deterministic computational framework for the exact orientational averaging and complete SO(3) decomposition of ab initio dynamic first- and second-hyperpolarizability tensors in isotropic media. The method combines analytical rotational averaging with irreducible tensor decomposition to transform molecular-frame Cartesian β and γ tensors into closed laboratory-frame expressions for nonlinear optical observables, eliminating the need for stochastic orientational sampling. For the dynamic first hyperpolarizability, the response is resolved into the J = 1a, J = 1b, J = 1ab, J = 2, and J = 3 sectors, while the dynamic second hyperpolarizability is decomposed into the L = 0, L = 1, L = 2a, L = 2b, L = 3, and L = 4 sectors, with the L = 2ab cross-invariant retained for the duplicated (L = 2) block. A key formal result is that the dynamic L = 2 contribution of γ must be treated as a matrix-valued channel operator because this irreducible representation occurs with multiplicity two; accordingly, it cannot, in general, be reduced to a single scalar invariant. The orientational averages are evaluated analytically through rank-6 and rank-8 rotational tensors, yielding a general Cartesian-to-channel workflow free of Monte Carlo noise. Benchmarking against Monte Carlo rotational sampling confirms the correctness of the analytical treatment. Application to six benzothiadiazole-based donor-acceptor chromophores illustrates how molecular asymmetry, acceptor strength, and excitation wavelength redistribute the nonlinear response across symmetry channels. The methodology is general and applicable to any molecular system for which dynamic hyperpolarizability tensors are available from electronic-structure calculations.

This study presents a comprehensive density functional theory (DFT) investigation of the double perovskite compounds K2AgSbX6 (X = Cl, F, I) using the generalized gradient approximation (GGA) and modified Becke-Johnson (mBJ) exchange-correlation functionals. The electronic, optical, elastic, and thermoelectric properties of these materials have been systematically analyzed to evaluate their potential for photovoltaic and thermoelectric applications. The novelty of this work lies in the comparative band-gap engineering of K2AgSbX6 through halide substitution, together with a combined assessment of optical absorption, mechanical stability, thermoelectric performance, spin-orbit coupling effects, and thermodynamic behavior. The calculated lattice constants, formation energies, and structural stability parameters confirm the thermodynamic stability of all three compounds. Electronic band structure calculations reveal semiconductor behavior with band gaps ranging from 0.373eV (K2AgSb6) to 2.07eV (K2AgSbF6) using GGA, and 1.041eV to 4.11eV using mBJ approximation. Including spin-orbit coupling slightly reduces the mBJ band gaps to 0.97eV for K2AgSbI6, 2.42eV for K2AgSbCl6, and 4.017eV for K2AgSbF6, with the strongest SOC influence observed for the iodine-based compound. Effective-mass calculations further show that K2AgSbI6 has the lowest carrier effective mass among the studied compounds, with values of 0.204m0, 0.226m0, and 0.231m0 using GGA, mBJ, and mBJ + SOC, respectively, indicating more favorable carrier transport compared with K2AgSbCl6 and K2AgSbF6. The optical properties demonstrate excellent absorption characteristics in the visible and near-infrared regions, making these materials promising candidates for solar cell applications. In particular, K2AgSbI6 exhibits low-energy absorption starting near ~ 1eV, supporting its relevance for visible/near-infrared optoelectronic response. Elastic property analysis indicates mechanical stability and ductile behavior for all compounds. Phonon-dispersion calculations show the absence of imaginary frequencies along the investigated high-symmetry directions, confirming the dynamical stability of K2AgSbCl6, K2AgSbF6, and K2AgSbI6. The thermoelectric properties show significant potential for energy harvesting applications, particularly at elevated temperatures. The highest thermoelectric figure of merit is obtained for K2AgSbI6, with ZT exceeding 1.0 at high temperature, whereas K2AgSbF6 shows the lowest ZT because of its wider band gap and reduced carrier activity. These results identify halide substitution as an effective route to tune the electronic, optical, and thermoelectric response of K2AgSbX6 double perovskites.

We report a combined experimental and theoretical investigation of the structural, electronic, elastic, and vibrational properties of triclinic Li2W2O7. The crystal structure was confirmed through Rietveld refinement, in good agreement with the reported triclinic model. Density functional theory (DFT) calculations within the DFT-GGA/PBE framework reproduce the experimental lattice parameters with deviations below 5%. Bader charge analysis reveals predominantly ionic Li-O interactions (Li ≈ +0.90e) combined with significant W-O covalency (W ≈ +2.98e), and electronic structure calculations show a wide O 2p → W 5d charge-transfer band gap characteristic of d0 tungstates. Elastic constant calculations confirm mechanical stability with moderate anisotropy. Raman spectroscopy supported by DFT phonon calculations enables reliable mode assignment, revealing pronounced Li atomic motion in many WO6 vibrations. Hirshfeld surface analysis indicates that Li···O/O···Li contacts dominate the crystal packing (≈55.7%), with a 22.15% void fraction in the framework. High-pressure Raman measurements up to 9.3 GPa show predominantly positive pressure coefficients and clear spectral modifications between 6.3 and 7.5 GPa, providing evidence for a pressure-induced structural phase transition driven by octahedral tilting and symmetry reduction. The pressure response is governed by the interplay between rigid WO6 octahedra and a more compressible Li-O sublattice.

The metallization of hydrogen is a prerequisite for the emergence of superconducting properties, along with those of hydrides. Chemical precompression has enabled a class of high-transition-temperature superconductors based on hydrogen-rich hydrides, whereas direct metallization of molecular hydrides remains challenging. In this study, we demonstrate the metallization of hydrogen confined within fixed two-dimensional graphene channels, which provide a nanoscale environment for effective compression. The confined hydrogen forms compressed molecular hydrides whose intermolecular H-H separations are significantly reduced compared to those in ambient molecular hydrogen. Electronic structure calculations reveal that all the hydrogens in both stacks exhibit metallic properties. The Fermi surface of both stacks exhibits a peculiar nesting pattern, suggesting enhanced electron-phonon coupling. These results identify graphene-confined hydrogen (graphene-H6) systems as a promising platform for achieving metallic hydrogen and potentially low-pressure, high-Tc superconductors.

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.

The present work investigates theoretically the conformational preferences for complexes between a series of donor alcohols MeChH, where Ch = O, S, Se, and Te, and a common acceptor molecule acetophenone (APh). The latter is characterized by two distinct regions of negative electrostatic potential: the directed lone pair electrons on the carbonyl oxygen and the diffuse electronic cloud on its π-ring. It is predicted that when MeOH is the donor, O-H···O hydrogen bonding (H-bonding) to the carbonyl oxygen of APh gives rise to the most preferred APh-MeOH conformer, while H-bonding to its π-cloud is less favored. However, such binding preferences alter remarkably when the heavier alcohols act as the donor. Electronic structure calculations, including those at the CCSD(T)/CBS limit, predict highest stability for conformers bound by a combination of π-hole and σ-hole interactions, both involving the heavy chalcogen atom. The former involves the interaction of its lone pair with the electron-deficient region above the carbonyl group of APh, while the latter involves a chalcogen-bond (Ch-bond) with the π-cloud of APh (Ch···π interaction). Also, the ChH···π H-bonded interactions involving the SH/SeH/TeH donor and the π-cloud on APh become increasingly stable as compared to their carbonyl-bound ChH···O H-bonded counterparts as we move down the group. A chalcogen-chalcogen (Ch···Ch) interaction with the carbonyl oxygen of APh is stabilized only for MeTeH, leading to a Te···O Ch-bond. The important role of heavy atom substitution in biomolecular recognition is thus highlighted. Observed modulations in binding preferences and in the very nature of the nonbonded interactions are attributable to a delicate interplay of electrostatic and dispersion interactions.

Following ultraviolet (UV) excitation, nitroaromatic molecules can undergo complex excited-state relaxation and photofragmentation processes that may generate reactive nitrogen oxide species (NOx). However, the excited-state dynamics associated with NOx formation remain incompletely understood. Here, we investigate the photochemistry of nitrobenzene using time-resolved X-ray absorption spectroscopy at the oxygen K-edge, combined with high-level electronic structure calculations. Upon 267 nm excitation in the gas phase, nitrobenzene undergoes rapid relaxation from the initially populated 1(LBππ*) state to the 1(nAπ*)/3(nAπ*) states, where a significant fraction of the population remains trapped for at least 100 ps rather than undergoing rapid internal conversion to the S0 state. Signatures of NO or NO2 formation are not observed within this time window at the current signal-to-noise ratio, indicating that photofragmentation remains a minor channel up to 100 ps. These results provide element-specific insight into nitroaromatic photochemistry and support a mechanism in which photofragmentation is delayed by transient excited-state trapping.