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In this article, the theoretical photoionization spectroscopy of the aziridine (C2H5N) molecule is investigated. To start with, we have optimized the geometry of this molecule at the neutral electronic ground state at the density functional theory/augmented correlation-consistent polarized valence triple zeta level of theory using the G09 program. The electronic structure calculations were restricted to the first six low-lying electronic states in order to account for the experimental photoelectron spectrum of the C2H5N molecule. The first six low-lying electronic states ( X ̃ 2 A ′ , A ̃ 2 A ′ , B ̃ 2 A ″ , C ̃ 2 A ″ , D ̃ 2 A ′ , and E ̃ 2 A ′ ) of the potential energy surfaces (PESs) are calculated by both equation of motion-ionization potential-coupled cluster singles and doubles and multi-configuration quasi-degenerate perturbation theory ab initio quantum chemistry methods along the dimensionless normal displacement coordinates in which multiple conical intersections were established among the considered electronic states. A (6 × 6) model vibronic Hamiltonian is constructed on a diabatic electronic basis, using the symmetry selection rules and Taylor series expansion. The Cs symmetry point group of the aziridine molecule leads to electronic states symmetry of either A′ or A″, and these states are close in energy, due to which the same symmetry electronic states avoid each other. To get a smooth diabatic PES, a fourfold diabatization scheme is used, which is implemented in the General Atomic and Molecular Electronic Structure Systems suite of programs. All the parameters used in the diabatic vibronic coupling model Hamiltonian are calculated in terms of the normal modes of vibrational coordinates. Finally, the vibronic model Hamiltonian constructed for the coupled six electronic states is used to solve both time-independent and time-dependent Schrödinger equations using the multi-configuration time-dependent Hartree program module to obtain the dynamical observables. The theoretical vibronic band structure is found to be in good accord with the available experimental results. [ABSTRACT FROM AUTHOR]

We propose a quantum tomography (QT) approach to retrieve the temporally evolving reduced density matrix in electronic state basis, where the populations and coherence between the ground state and excited state are reconstructed from the ultrafast electron diffraction signal. In order to showcase the capability of the proposed QT approach, we simulate the nuclear wavepacket dynamics and ultrafast electron diffraction of photoexcited pyrrole molecules using the ab initio quantum chemical CASSCF method. From the simulated time-resolved diffraction data, we retrieve the evolving density matrix in a crude diabatic representation basis and reveal the symmetry of the excited pyrrole wavepacket. Our QT approach opens the route to make a quantum version of "molecular movie" that covers the electronic degree of freedom and equips ultrafast electron diffraction with the power to reveal the coherence between electronic states, relaxation, and dynamics of population transfer. [ABSTRACT FROM AUTHOR]

Mixed thorium/uranium dioxide, (Th,U)O2, is under consideration for advanced nuclear fuel applications. Investigating the point defect structure and energy in this oxide is important for predicting its behavior as fuel. In this work, we use first-principles calculations based on the generalized gradient approximation (GGA)+Hubbard U approach to investigate the internal energy and entropy of the formation of point defects in Th1−xUxO2 at various compositions below x ≤ 0.5. Point defects including O vacancies, O interstitials, Th vacancies, Th interstitials, U vacancies, and U interstitials have all been considered with their charges ranging from neutral to the maximum nominal values. The observed trends have been explained in terms of electronic density of states. The valence band maxima of crystals that contain defects play a crucial role and exhibit variations depending on the U content and the applied charge. The temperature dependence of internal energy and entropy of formation of defects have also been examined. The internal energy of formation of defects was found to exhibit slowly varying or constant values with respect to changes in the U content, except at low values of x and low temperatures. The entropy of formation of defects was observed to decrease with increasing U content. It was additionally observed that the entropy of formation of vacancies increases with temperature, while that of interstitials decreases. This investigation further revealed that at 0 K, the cation vacancies and anion interstitials become increasingly favorable with increasing U content, while cation interstitials and anion vacancies become less favorable. [ABSTRACT FROM AUTHOR]

We report on a strategy to indirectly read out the spectrum of an electronic spin via polarization transfer to nuclear spins in its local environment. The nuclear spins are far more abundant and have longer lifetimes, allowing for repeated polarization accumulation in them. Subsequent nuclear interrogation can reveal information about the electronic spectral density of states. We experimentally demonstrate the method by reading out the ESR spectrum of nitrogen vacancy center electrons in diamond via readout of lattice 13C nuclei. Spin-lock control on the 13C nuclei yields a significantly enhanced signal-to-noise ratio for the nuclear readout. Spectrally mapped readout presents operational advantages in being background-free and immune to crystal orientation and optical scattering. We harness these advantages to demonstrate applications in underwater magnetometry. The physical basis for the "one-to-many" spectral map is itself intriguing. To uncover its origin, we develop a theoretical model that maps the system dynamics, involving traversal of a cascaded structure of Landau–Zener anti-crossings, to the operation of a tilted "Galton board." This work points to new opportunities for "ESR-via-NMR" in dilute electronic systems and in hybrid electron–nuclear quantum memories and sensors. [ABSTRACT FROM AUTHOR]

We present the chemical bonding and electronic properties of liquid methane at temperatures from 2000 to 4000 K and high densities of up to 3.0 g/cm3, calculated using ab initio molecular dynamics simulations in combination with the Mulliken population analysis. Bond-overlap populations and pair distribution functions are studied to investigate the evolution of electron delocalization accompanying atomic structure change as the density is increased. In addition, we also investigated the bandgap energy, electronic density of states, and spatial distribution of electron density. We observed that molecular hydrogen and C‒C bonds are formed after methane dissociates, and then the system undergoes a nonmetal–metal transition coinciding with hydrogen being transformed from the molecular to the atomic state. The C‒C bonds in the system retain covalent character, even at the highest density of 3.0 g/cm3. [ABSTRACT FROM AUTHOR]

Using density functional theory (DFT) calculations, we investigated the dissociative mechanism of H 2 S adsorption and its dissociation on both clean and oxygen covered Pd (100) surface. For adsorption mechanism, the site preference was considered for H 2 S and HS monomers on both surfaces. The results suggest that H 2 S is energetically adsorbed on high symmetry sites, particularly the hollow site, on clean surface and top site on O-covered Pd (100) surface. Chemisorption of HS is stronger than H 2 S at the favorable hollow site on clean surface and O-covered surface. The energy barriers for S–H bond-breaking during the first H 2 S dehydrogenation are 0.35, 0.07, 0.32, and 0.16 eV, while for second dehydrogenation are 0.32 and 0.30 eV, respectively. On the oxygen-covered surface, the H 2 S adsorption site transitions from bridge to the top site and their energy barrier for first-order decomposition is 0.05 eV, significantly lesser than that observed on a clean surface. To examine more, the electronic densities of states as well as d-band center model were used to characterize the interaction of adsorbed H 2 S with the surfaces. Overall, our findings show that H 2 S decomposition on these surfaces is exothermic and relatively easy, but the presence of surface oxygen hinders the breaking process of H–S bond due to kinetic and thermodynamic factors. • Explored poisoning mechanism via H 2 S adsorption and dissociation on clean & O–Pd (100). • H 2 S favors hollow sites on clean Pd (100) and top sites on O–Pd (100) during adsorption. • The H 2 S adsorption site near atomic oxygen shifts to the top site from bridge site. • The potential energy profile for H 2 S decomposition was mapped on both surfaces. • H 2 S decomposition on clean and O–Pd (100) surface is a facile process. [ABSTRACT FROM AUTHOR]

The exceptional synergy of ceramic and metallic properties within MAX phases positions them as highly promising for a wide array of applications. However, their stability has been threatened by the phenomenon of A-site metal whisker growth. Herein, we have significantly mitigated tin whisker growth in Ti 2 SnC by incorporating vanadium solutes at its M-site. With an increase in vanadium concentration, there is a marked reduction in the degree of decomposition of the M-site solid solution when subjected to the same level of externally destructive treatments, thereby inhibiting whisker proliferation. Both experimental outcomes and theoretical calculations reveal that the vanadium solid solution augments the hardness, Pugh's ratio, and Poisson's ratio of Ti 2 SnC, enhancing its mechanical strength and toughness. The incorporation of V atoms introduces stronger V–C and V–Sn bonds, as evidenced by its electronic density of states and bulk modulus, thus significantly bolstering the resistance of MAX phases against decomposition and effectively curtailing whisker growth. Additionally, the phenomenon reported in this paper also conforms to the electrostatic theory of whisker growth. This work for the first time achieves the suppression of A-site whisker growth through an M-site solid solution, thereby extending their potential for applications where durability and reliability are paramount. [ABSTRACT FROM AUTHOR]

First-principles simulations are conducted to explore the structural stability, electronic properties, and optical responses of pristine and boron- or nitrogen-doped monolayers graphene. The computed electronic density of states revealed that the substitutional doping of boron impurity atoms on monolayer graphene (MLG) shifts the Dirac point upward, although the substitution of nitrogen impurity atoms in graphene pushes the Dirac point downward the Fermi level. This could exhibit that upon the doping of MLG with boron or nitrogen, respectively, p-type or n-type semimetal is acquired. The overall optical spectral properties of the substituted graphene with boron or nitrogen atoms are simulated and compared with the optical spectra results of pure graphene. The optical features of pristine and doped MLG are determined by taking the interband and intra-band transitions into account ranging from the far-infrared to the ultraviolet regime of the electromagnetic radiation. A remarkable red shift in the optical spectra of the doped MLG towards the visible regime of radiation is established. An enhanced reflectivity illustrated that concentration-dependent optical properties of boron and nitrogen-doped MLG happen at lower electromagnetic radiation regimes. In addition, we explored the thermoelectric behaviors of the pristine/doped graphene monolayers with 4 × 4 supercells. We found a significant improvement in the electrical conductivity of graphene when doped with boron or nitrogen impurities. However, an increase in the electrical conductivity has textured a decrease in the Seebeck coefficients. Improvement in the electrical conductivity is attributed to an interesting effect on the graphene monolayers' power factor (PF). These findings indicate a positive impact of the dopants on the thermoelectric properties of graphene monolayers and reveal that they are potential materials for thermoelectric applications and nanodevices. [ABSTRACT FROM AUTHOR]

1D grain boundaries in transition metal dichalcogenides (TMDs) are ideal for investigating the collective electron behavior in confined systems. However, clear identification of atomic structures at the grain boundaries, as well as precise characterization of the electronic ground states, have largely been elusive. Here, direct evidence for the confined electronic states and the charge density modulations at mirror twin boundaries (MTBs) of monolayer NbSe2, a representative charge‐density‐wave (CDW) metal, is provided. The scanning tunneling microscopy (STM) measurements, accompanied by the first‐principles calculations, reveal that there are two types of MTBs in monolayer NbSe2, both of which exhibit band bending effect and 1D boundary states. Moreover, the intrinsic CDW signatures of monolayer NbSe2 are dramatically suppressed as approaching an isolated MTB but can be either enhanced or suppressed in the MTB‐constituted confined wedges. Such a phenomenon can be well explained by the MTB‐CDW interference interactions. The results reveal the underlying physics of the confined electrons at MTBs of CDW metals, paving the way for the grain boundary engineering of the functionality. [ABSTRACT FROM AUTHOR]

The appearance of van Hove singularities near the Fermi level leads to prominent phenomena, including superconductivity, charge density wave, and ferromagnetism. Here a bilayer Kagome lattice with multiple van Hove singularities is designed and a novel borophene with such lattice (BK‐borophene) is proposed by the first‐principles calculations. BK‐borophene, which is formed via three‐center two‐electron (3c–2e) σ‐type bonds, is predicted to be energetically, dynamically, thermodynamically, and mechanically stable. The electronic structure hosts both conventional and high‐order van Hove singularities in one band. The conventional van Hove singularity resulting from the horse saddle is 0.065 eV lower than the Fermi level, while the high‐order one resulting from the monkey saddle is 0.385 eV below the Fermi level. Both the singularities lead to the divergence of electronic density of states. Besides, the high‐order singularity is just intersected to a Dirac‐like cone, where the Fermi velocity can reach 1.34 × 106 m s−1. The interaction between the two Kagome lattices is critical for the appearance of high‐order van Hove singularities. The novel bilayer Kagome borophene with rich and intriguing electronic structure offers an unprecedented platform for studying correlation phenomena in quantum material systems and beyond. [ABSTRACT FROM AUTHOR]

A density functional theory based calculations are performed to investigate structural, hydrogen storage, mechanical, electronic and thermodynamical properties of lead-free hydride perovskites XGeH 3 (X=Cs, Fr). The optimized lattice constant and hence volume against the minimum energy is obtained and found to be 4.176 Å and 4.184 Å for CsGeH 3 and FrGeH 3 respectively. The gravimetric and volumetric hydrogen storage capacity of 1.43% and 1.00%, 72.81 (g.H 2 / L) and 73.21 (g.H 2 / L) for CsGeH 3 and FrGeH 3 respectively. The density of states and electronic band structure predicted the metallic nature of both hydrides which was affirmed by the Fermi Surfaces. The calculation of Poisson's, Pugh's ratio and Cauchy's pressure suggested their brittle nature. The Debye temperature decreases with the increase of temperature while volume and entropy increase by increasing applied temperature. The present study shows the potential of lead-free hydride perovskites in hydrogen storage applications due to rather suitable gravimetric hydrogen capacity and high stability. • Hydrogen storage capacity of XGeH 3 (X = Cs, Fr) are investigated. • Gravimetric and volumetric hydrogen storage capacity of hydrides are calculated. • XGeH 3 (X = Cs, Fr) hydrides exhibit mechanical and thermodynamical stability. • Both compounds show metallic nature with 0 eV band gap. • Mechanical properties predict brittle nature of XGeH 3 (X = Cs, Fr). [ABSTRACT FROM AUTHOR]

AlB2${\rm AlB}_{2}$‐type TaB2${\rm TaB}_{2}$ is one of the transition‐metal diborides, a class of refractory ceramics, that has increasingly received attention due particularly to their potential for hard‐coating applications. In this work, the first‐principles calculations are performed, in combination with the cluster‐expansion method, to investigate the effect of mixing AlB2${\rm AlB}_{2}$ with TaB2${\rm TaB}_{2}$ on the thermodynamic stability, structural parameters, electronic density of states, and mechanical behavior of the resulting (Ta,Al)B2${\rm B}_{2}$ solid solutions. It is found that the solid solutions display the chemical ordering of Ta and Al atoms both residing on the metal sublattice of the material, together with the preference for partial substitution of vacancies for Al atoms. This results in the formation of Al‐deficient (Ta,Al)B2${\rm B}_{2}$ with the chemical composition Ta0.6Al0.3B2${\rm Ta}_{0.6} {\rm Al}_{0.3} {\rm B}_{2}$, predicted to be thermodynamically stable even at absolute zero in the ternary Ta−Al−B system. It is further found that such formation of Al vacancies in (Ta,Al)B2${\rm B}_{2}$ not only enhances the stability of the solutions but also improves their elastic properties and hardness, both of which could be attributed to the effect of electronic band filling. This investigation indeed sheds light on the interplay between the mixing of Ta and Al atoms and the presence of Al vacancies on the alloying and mechanical behaviors of (Ta,Al)B2${\rm B}_{2}$, and it thus offers valuable insights for further research and development of these ceramics. [ABSTRACT FROM AUTHOR]

Organic materials have found widespread applications but require doping to overcome their intrinsically low carrier concentration. Doping injects free carriers into the polymer, moving the position of the Fermi level, and creates coulombic traps, changing the shape of the electronic density of states (DOS). We develop equations to explicitly map the DOS parameters to the Seebeck vs conductivity relationship. At low carrier concentrations, this relationship is a universal slope - k B / q , while at higher carrier concentrations, the slope becomes dependent on the shape of the DOS. We conclude that, at high doping, a heavy-tailed DOS leads to higher thermoelectric power factors. [ABSTRACT FROM AUTHOR]

Polylactic acid modified with graphene oxide (PLA/GO) is proposed to interact with ZnO through 6 different schemes. Density functional theory at B3LYP/LANL2DZ level was utilized to calculate total dipole moment (TDM), HOMO/LUMO energy gap (ΔE) and to map the molecular electrostatic potential (MESP). Results indicated that PLA/GO interacted with ZnO through O-atom forming PLA/GO/OZn composite. This composite interacts with methane, hydrogen sulfide, humidity (H2O), carbon dioxide and ethanol. The same gases were supposed to interact further with PLA/GO/Cu2O. Adsorption energy for the interaction between each composite and the proposed gases were calculated. Both PLA/GO/OZn and PLA/GO/Cu2O composites interacted favorably with H2O. Adsorption energy for interaction of other gases with studied structures are generally low compared to H2O. PLA/GO/OZn have adsorption energy slightly higher than that of PLA/GO/Cu2O. PLA/GO/OZn has higher TDM values than those of PLA/GO/Cu2O, indicating a more polar material. Conversely, PLA/GO/Cu2O exhibited larger ΔE values than those of PLA/GO/OZn. TDM and energy gap results for both studied structures indicated good sensing capabilities. Further insights come from analyzing the calculated density of states (DOS) and partial density of states (PDOS). PLA/GO/Cu2O exhibited high peak for copper in its DOS and PDOS spectra compared to zinc and oxygen in case of PLA/GO/OZn. This means a higher density of available electronic states associated with Cu. [ABSTRACT FROM AUTHOR]

Achieving superconductivity at room temperature (RT) is a holy grail in physics. Recent discoveries on high‐Tc superconductivity in binary hydrides H3S and LaH10 at high pressure have directed the search for RT superconductors to compress hydrides with conventional electron–phonon mechanisms. Here, an exceptional family of superhydrides is predicated under high pressures, MH12 (M = Mg, Sc, Zr, Hf, Lu), all exhibiting RT superconductivity with calculated Tcs ranging from 313 to 398 K. In contrast to H3S and LaH10, the hydrogen sublattice in MH12 is arranged as quasi‐atomic H2 units. This unique configuration is closely associated with high Tc, attributed to the high electronic density of states derived from H2 antibonding states at the Fermi level and the strong electron–phonon coupling related to the bending vibration of H2 and H‐M‐H. Notably, MgH12 and ScH12 remain dynamically stable even at pressure below 100 GPa. The findings offer crucial insights into achieving RT superconductivity and pave the way for innovative directions in experimental research. [ABSTRACT FROM AUTHOR]

Semiconducting clathrates have attracted considerable interest in the field of thermoelectric materials. We report here a computational study on the crystal structure, the enthalpy of formation, and the physical properties of the following type-I clathrates: (a) experimentally studied Cs8Sn44 and hypothetical Cs8Sn46 and (b) hypothetical (NH4)8Sn46−x (x = 0 or 2). The ab initio VASP calculations for the nominal stoichiometries include the geometry optimization of the initial structural models, enthalpies of formation, and the electronic and phonon density of states. Comparison of the chemical bonding of the structural models is performed via the electron localization function. The results show that the presence and distribution of defects in the Sn framework for both Cs8Sn46−x and (NH4)8Sn46−x systems significantly alters the formation energy and its electrical properties, ranging from metallic to semiconducting behavior. In particular, one defect per six-membered Sn ring in a 3D spiro-network is the thermodynamically preferred configuration that results in the Cs8Sn44 and (NH4)8Sn44 stoichiometries with narrow-band gap semiconducting behavior. Moreover, the rotation of the ammonium cation in the polyhedral cavities is an interesting feature that may promote the use of ammonium or other small molecular cations as guests in clathrates for thermoelectric applications; this is due to the decrease in the lattice thermal conductivity. [ABSTRACT FROM AUTHOR]

Developing earth‐abundant low‐cost electrocatalysts is of prime research interest towards the need for clean energy technology, such as water‐splitting reactions. Herein, we have explored the electrocatalytic activity of the double perovskite‐based strontium cobalt molybdenum oxide (SCMO) towards water‐splitting reactions, both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in harsh alkaline condition (1 M KOH). Prepared by scalable autocombustion synthesis, the as‐synthesised bulk SCMO perovskite exhibited impressive electrocatalytic performance attributed to its substantial electrochemical active surface area, measured at 26.3 cm2. For the OER, it exhibited an overpotential of 350 mV with a Tafel slope value of 76 mV/dec. Concurrently, it showed proficient activity in the HER, revealing an overpotential of 270 mV and a Tafel slope of 112 mV/dec. Further, this perovskite material was stable during continuous electrocatalysis over a 24 h period in harsh alkaline media with a negligible increase in observed overpotential value. The electronic density of states confirmed that the Co plays a pivotal role in enhancing electrocatalytic activities. This is achieved by a substantial reduction in the band gap and enhancement of the d‐band centre to an optimal level, rendering the system more favourable for electrocatalytic reactions. Our study contributes essential insights to the advancement of the design and utilization of perovskite‐based catalysts in the realm of sustainable energy technologies. [ABSTRACT FROM AUTHOR]

Electrodeposition of abundant metals to fabricate efficient and durable electrodes indicate a viable role in advancing renewable electrochemical energy tools. Herein, we deposit Co9S8‐Ag‐Ni3S2@NF on nickel foam (NF) to produce Co9S8‐Ag‐Ni3S2@NF as a exceedingly proficient electrode for oxygen evolution reaction (OER). The electrochemical investigation verifies that the Co9S8‐Ag‐Ni3S2@NF electrode reveals better electrocatalytic activity to OER because of its nanoflowers′ open‐pore morphology, reduced overpotential (η10=125 mV), smaller charge transfer resistance, long‐term stability, and a synergistic effect between various components, which allows the reactants to be more easily absorbed and subsequently converted into gaseous products during the water electrolysis route. Density functional theory (DFT) calculation as well reveals the introduction of Ag (222) surface into the Co9S8 (440)‐Ni3S2 (120) structure increases the electronic density of states (DOS) per unit cell of a system and increases the electrocatalytic activity of OER by considerably lowering the energy barriers of its intermediates. This study provides the innovation of employing trimetallic nanomaterials immobilized on a conductive, continuous porous three‐dimensional network formed on a nickel foam (NF) substrate as a highly proficient catalyst for OER. [ABSTRACT FROM AUTHOR]

The organic compound 7–hydroxy–4–methyl coumarin, also known as 4–methylumbelliferone or hymecromone, belongs to the lactone family. The compound's molecular geometry, the bond angle, and the bond length of its dimers were determined by theoretical calculations using the software packages Gaussian 09W and Multiwfn 3.8. The most stable form of the 7–hydroxyl–4–methyl coumarin molecule is found to be a syn-ht dimer with an energy of −1223.1466 (a.u.).VEDA 4 software was used to determine vibrational assignments and PED values to gain insight into the structural details of these dimers. The vibrations of dimers formed from the same monomer showed remarkable differences. To support the chemical reactivity of the dimers, the HOMO–LUMO energy gap, MEP, and ALIE maps were analyzed. The anti-hh dimer was found to be highly polarizable and reactive in both solvent and gaseous media. In addition, Fukui functions were used to analyze the electrophilic (E +) and nucleophilic (Nu-) sites. The electronic excitation and UV–vis spectra were predicted using the time–dependent density functional theory (DFT) method. RDG-NCI and AIM analyses were utilized for predicting weak interactions between dimer molecules. Electronic parameters such as density of states (DOS) analysis, transition density matrix (TDM), and energy levels of electrons and holes were also analyzed. Based on the theoretical analysis, it is evident that this particular molecule exhibits a propensity for dimerization, with the resulting dimers showing considerable potential for advancement in various fields, particularly in the field of polymers and materials. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive investigation into the electronic properties of Hydroxyapatite (HAp) doped with Zinc (Zn) and Cobalt (Co). Five distinct compositions, denoted as 0.15Zn-HAp, 0.15Co-0.15Zn-HAp, 0.30Co-0.15Zn-HAp, 0.45Co-0.15Zn-HAp, and 0.6Co-0.15Zn-HAp (at%,) have been systematically studied employing Density of States (DOS) and band structure calculations. The computed band gap values for these compositions were determined to be 4.6663, 4.6888, 4.7049, 4.7159, and 4.7082 eV, respectively. These results illuminate the profound influence of Zn and Co doping on the electronic structure of Hydroxyapatite. These findings hold significant implications for the potential applications of these materials in diverse technological and biomedical domains. The systematic approach and precise electronic property characterizations presented in this study provide a robust foundation for further advancements in the realm of advanced materials, with particular relevance to the development of innovative materials for use in cutting-edge technologies and medical applications. [ABSTRACT FROM AUTHOR]

This study employs density functional theory (DFT) and molecular dynamics to meticulously investigate the structural and electronic properties of ternary chalcogenide compounds, specifically (GeTe4)1-x Inx, and (GeTe5)1-x Inx across a range of compositions ( x = 0, 5, 10, 15, 20 at %). Utilizing the local density approximation within the framework of first-principles calculations, we comprehensively analyze the pair correlation function, static structural factor, electronic density of states, and electronic band gap energy. Our results reveal a notable decrease in the energy band gap of Germanium-Tellurium with the incorporation of Indium atoms. The structural changes observed in the Ge-Te matrix with Indium doping, as evidenced by the changes in the pair correlation function and static structure factor, are consistent with and supportive of the observed decrease in the band gap energy. This phenomenon is primarily attributed to the significant contribution of Indium atoms to the conduction band edge, offering new insights into the material's electronic behaviour. [ABSTRACT FROM AUTHOR]

The transmittance, reflectivity, and photoluminescence in the range 0.8–1.7 eV at 300 K and 77 K in the spectral range 0.6–6.0 eV at 300 K of thin films of CdTe synthesized on different substrates by thermal evaporation in a quasi-closed volume were studied. A strong dependence of the intensity and position of the band–band and excitonic luminescence bands on the substrate quality was discovered. The excitonic luminescence bands of films on silicon and glass were shifted by 10 meV to the short-wavelength region because of internal stresses in the films owing to the mismatch between the unit-cell parameters of the substrate and film. The transparency region of films cleaved from glass shifted to the longwavelength region because of the density tails of electronic states in the band gap caused by disordering of the films and the longer wavelength of the light than the roughness of the films on the growth and nucleation side. The best structural perfection was characteristic of films on a CdTe substrate based on the obtained dependences of the intensity and spectral position of the photoluminescence lines. [ABSTRACT FROM AUTHOR]

We report a Kohn–Sham density functional theory calculation of a system with more than 200 000 atoms and 800 000 electrons using a real-space high-order finite-difference method to investigate the electronic structure of large spherical silicon nanoclusters. Our system of choice was a 20 nm large spherical nanocluster with 202 617 silicon atoms and 13 836 hydrogen atoms used to passivate the dangling surface bonds. To speed up the convergence of the eigenspace, we utilized Chebyshev-filtered subspace iteration, and for sparse matrix–vector multiplications, we used blockwise Hilbert space-filling curves, implemented in the PARSEC code. For this calculation, we also replaced our orthonormalization + Rayleigh–Ritz step with a generalized eigenvalue problem step. We utilized all of the 8192 nodes (458 752 processors) on the Frontera machine at the Texas Advanced Computing Center. We achieved two Chebyshev-filtered subspace iterations, yielding a good approximation of the electronic density of states. Our work pushes the limits on the capabilities of the current electronic structure solvers to nearly 106 electrons and demonstrates the potential of the real-space approach to efficiently parallelize large calculations on modern high-performance computing platforms. [ABSTRACT FROM AUTHOR]

We investigate the source of error in the Thomas–Fermi–von Weizsäcker (TFW) density functional relative to Kohn–Sham density functional theory (DFT). In particular, through numerical studies on a range of materials, for a variety of crystal structures subject to strain and atomic displacements, we find that while the ground state electron density in TFW orbital-free DFT is close to the Kohn–Sham density, the corresponding energy deviates significantly from the Kohn–Sham value. We show that these differences are a consequence of the poor representation of the linear response within the TFW approximation for the electronic kinetic energy, confirming conjectures in the literature. In so doing, we find that the energy computed from a non-self-consistent Kohn–Sham calculation using the TFW electronic ground state density is in very good agreement with that obtained from the fully self-consistent Kohn–Sham solution. [ABSTRACT FROM AUTHOR]

Nb x Re 1 − x is a non-centrosymmetric superconductor recently realized in thin film form. The access to the basic physics that governs this material is hindered by the polycrystalline structure of the films which consist of grains of small dimensions. In these conditions, films are not decisive in revealing the nature of the superconducting order parameter, and, in particular, the possible presence of a spin-triplet component. In this work, post-deposition annealing procedures were performed to improve the crystalline quality of the as-grown films. As determined by x-ray diffraction measurements, by tuning the annealing process, it was possible to increase the crystalline size from 1–2 nm up to several nanometers, beyond the values of the superconducting coherence length. Pair distribution function analyses revealed the non-centrosymmetric crystal structure of the treated NbRe films. Finally, electrical transport measurements, performed to study the relationship between structural and transport properties of the samples, showed an improved metallicity and a reduction of the superconducting critical temperature after the thermal treatment. This last result can be reasonably ascribed, for instance, to oxygen contamination, modification of the electronic density of states at the Fermi level, or change in the electron–phonon coupling. The results of this work are useful to realize films for future experiments meant to access nature of the superconducting order parameter. [ABSTRACT FROM AUTHOR]

We report the in-plane electron transport in the MXenes (i.e., within the MXene layers) as a function of composition using the density-functional tight-binding method, in conjunction with the non-equilibrium Green's functions technique. Our study reveals that all MXene compositions have a linear relationship between current and voltage at lower potentials, indicating their metallic character. However, the magnitude of the current at a given voltage (conductivity) has different trends among different compositions. For example, MXenes without any surface terminations (Ti3C2) exhibit higher conductivity compared to MXenes with surface functionalization. Among the MXenes with –O and –OH termination, those with –O surface termination have lower conductivity than the ones with –OH surface terminations. Interestingly, conductivity changes with the ratio of –O and –OH on the MXene surface. Our calculated I–V curves and their conductivities correlate well with transmission functions and the electronic density of states around the Fermi level. The surface composition-dependent conductivity of the MXenes provides a path to tune the in-plane conductivity for enhanced pseudocapacitive performance. [ABSTRACT FROM AUTHOR]

In Born–Oppenheimer molecular dynamics (BOMD) simulations based on the density functional theory (DFT), the potential energy and the interatomic forces are calculated from an electronic ground state density that is determined by an iterative self-consistent field optimization procedure, which, in practice, never is fully converged. The calculated energies and forces are, therefore, only approximate, which may lead to an unphysical energy drift and instabilities. Here, we discuss an alternative shadow BOMD approach that is based on backward error analysis. Instead of calculating approximate solutions for an underlying exact regular Born–Oppenheimer potential, we do the opposite. Instead, we calculate the exact electron density, energies, and forces, but for an underlying approximate shadow Born–Oppenheimer potential energy surface. In this way, the calculated forces are conservative with respect to the approximate shadow potential and generate accurate molecular trajectories with long-term energy stabilities. We show how such shadow Born–Oppenheimer potentials can be constructed at different levels of accuracy as a function of the integration time step, δt, from the constrained minimization of a sequence of systematically improvable, but approximate, shadow energy density functionals. For each energy functional, there is a corresponding ground state Born–Oppenheimer potential. These pairs of shadow energy functionals and potentials are higher-level generalizations of the original "zeroth-level" shadow energy functionals and potentials used in extended Lagrangian BOMD [Niklasson, Eur. Phys. J. B 94, 164 (2021)]. The proposed shadow energy functionals and potentials are useful only within this extended dynamical framework, where also the electronic degrees of freedom are propagated as dynamical field variables together with the atomic positions and velocities. The theory is quite general and can be applied to MD simulations using approximate DFT, Hartree–Fock, or semi-empirical methods, as well as to coarse-grained flexible charge models. [ABSTRACT FROM AUTHOR]

A hybrid atomistic-continuum method can model the microstructure evolution of metals subjected to laser irradiation. This method combines classical molecular dynamics (MD) simulations with the two-temperature model (TTM) to account for the laser energy absorption and heat diffusion behavior. Accurate prediction of the temperature evolution in the combined MD-TTM method requires reliable accuracy in electron heat capacity, electron thermal conductivity, and electron–phonon coupling factor across the temperatures generated. This study uses the electronic density of states (DOS) obtained from first-principle calculations. The calculated electron temperature-dependent parameters are used in MD-TTM simulations to study the laser metal interactions in FCC and BCC metals and the phenomenon of laser shock loading and melting. This study uses FCC Al and BCC Ta as model systems to demonstrate this capability. When subjected to short pulsed laser shocks, the dynamic failure behavior predicted using temperature-dependent parameters is compared with the experimentally reported single-crystal and nanocrystalline Al and Ta systems. The MD-TTM simulations also investigate laser ablation and melting behavior of Ta to compare with the ablation threshold reported experimentally. This manuscript demonstrates that integrating the temperature-dependent parameters into MD-TTM simulations leads to the accurate modeling of the laser–metal interaction and allows the prediction of the kinetics of the solid–liquid interface. [ABSTRACT FROM AUTHOR]

Because of their quantum confinement effects and adjustable features, semiconductor nanoparticles have attracted a lot of attention for their various uses in optoelectronic devices. This study investigates how size and shape variations affect the optoelectronic properties of semiconductor nanoparticles InX (X = As, Sb, and P). Using unified thermodynamics modeling, it explores the effects of these nanoparticles' diameters on their electronic band structures, optical properties, and charge carrier dynamics. The inquiry focuses on InX nanoparticles with different sizes and nanostructure morphologies. By examining electronic band structures, the density of states, and optical absorption spectra, the size-dependent quantum confinement processes that govern the optical band gap transitions and excitonic behaviors in these semiconductor nanoparticles were made clear. Also, the influence of the shape of the nanoparticles on carrier mobility and electronic band alignment is investigated, offering insights into the possibility of controlling the morphology to customize optoelectronic capabilities. This theoretical analysis indicates that altering the optoelectronic properties of InX semiconductor nanoparticles is mostly dependent on their size and shape. Smaller nanoparticles show stronger quantum size effects, which lead to improved exciton confinement and blue shifts in the optical absorption spectra. Shape-dependent differences in the density of states and electronic band structures indicate the impact of morphology on the dynamics and recombination of charge carriers in the nanoparticles. In conclusion, this work provides important insights for the design and optimization of semiconductor nanomaterials for photovoltaic, sensing, and light-emitting applications by thoroughly examining the impact of size and shape on the optoelectronic properties of InX semiconductor nanoparticles. [ABSTRACT FROM AUTHOR]

Aromatic amines are important commercial chemicals, but their carcinogenicity poses a threat to humans and other organisms, making their rapid quantitative detection increasingly urgent. Here, amorphous MoO3 (a‐MoO3) monolayers with localized surface plasmon resonance (LSPR) effect in the visible region are designed for the trace detection of carcinogenic aromatic amine molecules. The hot‐electron fast decay component of a‐MoO3 decreases from 301 fs to 150 fs after absorption with methyl orange (MO) molecules, indicating the plasmon‐induced hot‐electron transfer (PIHET) process from a‐MoO3 to MO. Therefore, a‐MoO3 monolayers present high SERS performance due to the synergistic effect of electromagnetic enhancement (EM) and PIHET, proposing the EM‐PIHET synergistic mechanism in a‐MoO3. In addition, a‐MoO3 possesses higher electron delocalization and electronic state density than crystal MoO3 (c‐MoO3), which is conducive to the PIHET. The limit of detection (LOD) for o‐aminoazotoluene (o‐AAT) is 10−9 M with good uniformity, acid resistance, and thermal stability. In this work, trace detection and identification of various carcinogenic aromatic amines based on a‐MoO3 monolayers is realized, which is of great significance for reducing cancer infection rates. [ABSTRACT FROM AUTHOR]

Resonant inelastic x-ray scattering (RIXS) is a widely used spectroscopic technique, providing access to the electronic structure and dynamics of atoms, molecules, and solids. However, RIXS requires a narrow bandwidth x-ray probe to achieve high spectral resolution. The challenges in delivering an energetic monochromated beam from an x-ray free electron laser (XFEL) thus limit its use in few-shot experiments, including for the study of high energy density systems. Here we demonstrate that by correlating the measurements of the self-amplified spontaneous emission (SASE) spectrum of an XFEL with the RIXS signal, using a dynamic kernel deconvolution with a neural surrogate, we can achieve electronic structure resolutions substantially higher than those normally afforded by the bandwidth of the incoming x-ray beam. We further show how this technique allows us to discriminate between the valence structures of Fe and Fe2O3, and provides access to temperature measurements as well as M-shell binding energies estimates in warm-dense Fe compounds. The authors combine differentiable physics modelling and neural networks to extract high-resolution electronic density of states of warm dense materials from resonant inelastic x-ray scattering spectra. With this approach, they identify distinctive features in the valence structures of warm dense Fe and Fe2O3, also estimating their temperature and M-shell binding energies. [ABSTRACT FROM AUTHOR]

This article examines the optoelectronic and transport properties of ZnxAxSiGeN4 (A = Mn, Eu) through a comprehensive study. The study utilizes first-principles density functional theory (DFT) calculations with the Wien2k code. The optimized structural parameters, including the tolerance factor, critical radius, and formation energy, were initially determined. The energy band structure, densities of electronic states, and energy dependence of the optical functions were determined. The observed phenomenon exhibits a reduction in the energy difference between the valence and conduction bands for the materials under investigation. Precisely, the band gaps were measured to 4.1 eV, 2.0 eV (up)/2.8 eV (dn), and 0.8 eV (up)/2.4 eV (dn), respectively, for the respective doping of Eu and Mn. It has been determined that the material exhibits a direct band gap with a transition occurring along the Γ–Γ symmetry point. The electronic interband changes responsible for the observed optical spectra were identified. The thermoelectric parameters, such as the Seebeck coefficient, electrical and thermal conductivities, and figure of merit, were calculated using the standard Boltzmann transport theory in parallel. Based on our findings, it has been determined that the compounds under investigation exhibit promising characteristics that make them viable contenders for utilization in thermoelectric applications. The process of doped compounds Zn0.95Eu0.05SiGeN4 and of Zn0.95Mn0.05SiGeN4 has the potential to alter the characteristics of the material significantly, suggesting being promising for utilization in emerging fields such as advanced electronics and photovoltaic. [ABSTRACT FROM AUTHOR]

Regulating the crystal morphology of low aspect ratio, short columnar α‐hemihydrate gypsum (α‐HH) is crucial due to its distinctive physical and chemical properties, which make it widely applicable. In this work, succinic acid, malic acid, and maleic acid were selected as the research objects, among which the number and spacing of carboxyl groups were the same, while the auxiliary functional groups were different. The adsorption energy, Mulliken charge population, electronic state density, and charge density difference of the three organic acids on the surfaces of α‐HH were calculated by well‐defined ab initio calculations. The results showed that the synergistic effect of ‐COOH groups is necessary for the effective crystallization of α‐HH. Organic acids interact with the Ca atoms on the crystal surface, as evidenced by their preferential adsorption on the top surface of α‐HH crystals (002). This interaction occurs through a double‐dentate chelation between the carboxyl oxygen atoms at both ends of the organic acid and the Ca atoms on the crystal surface, resulting in the formation of a six‐membered cyclic organic acid calcium complex. This complex hinders ion diffusion and the stacking of crystal surfaces, leading to a decrease in the growth rate along the c‐axis and promoting more extensive crystal development and larger crystal sizes. The work provides insight into the preparation of short prismatic α‐HH using organic acid crystallizing agents. [ABSTRACT FROM AUTHOR]

This brief review covers the thermoelectric properties of one-dimensional materials, such as nanowires and nanotubes. The highly localised peaks of the electronic density of states near the Fermi levels of these nanostructured materials improve the Seebeck coefficient. Moreover, quantum confinement leads to discrete energy levels and a modified density of states, potentially enhancing electrical conductivity. These electronic effects, coupled with the dominance of Umklapp phonon scattering, which reduces thermal conductivity in one-dimensional materials, can achieve unprecedented thermoelectric efficiency not seen in two-dimensional or bulk materials. Notable advancements include carbon and silicon nanotubes and Bi3Te2, Bi, ZnO, SiC, and Si1−xGex nanowires with significantly reduced thermal conductivity and increased ZT. In all these nanowires and nanotubes, efficiency is explored as a function of the diameter. Among these nanomaterials, carbon nanotubes offer mechanical flexibility and improved thermoelectric performance. Although carbon nanotubes theoretically have high thermal conductivity, the improvement of their Seebeck coefficient due to their low-dimensional structure can compensate for it. Regarding flexibility, economic criteria, ease of fabrication, and weight, carbon nanotubes could be a promising candidate for thermoelectric power generation. [ABSTRACT FROM AUTHOR]

Based on the first principles, the structural stability, mechanical characteristics, electronic structure, and thermodynamic properties of AlCu2M (M = Ti, Cr, Zr, Sc, Hf, Mn, Pa, Lu, Pm) are investigated. The calculated results indicate that the AlCu2Pa crystal structure is more stable and that AlCu2Pa should be easier to form. All of the AlCu2M compounds have structural stability in the ground state. Elastic constants are used to characterize the mechanical stability and elastic modulus, while the B/G values and Poisson ratio demonstrate the brittleness and ductility of AlCu2M compounds. It is demonstrated that all computed AlCu2M compounds are ductile and mechanically stable, with AlCu2Hf having the highest bulk modulus and AlCu2Mn having the highest Young's modulus. AlCu2Mn has the highest intrinsic hardness among AlCu2M compounds, according to calculations of their intrinsic hardness. The electronic densities of states are discussed in detail; it was discovered that all AlCu2M compounds form Al-Cu and Al-M covalent bonds. Additionally, we observe that the Debye temperature and minimum thermal conductivity of AlCu2Mn and AlCu2Sc are both larger than those of others, indicating stronger chemical bonds and higher thermal conductivities, which is consistent with the elastic modulus results. [ABSTRACT FROM AUTHOR]

In this study, the electronic density of states (DOSs) calculated with density functional theory (DFT) were analyzed by the machine‐learning techniques. More than 400 pure metal and bimetallic alloy systems were calculated with DFT, and obtained the surface DOSs and the CH3 adsorption energy (Ead). By fitting the Gaussian functions to the DOS, multiple descriptors, such as the Gaussian peak positions, heights, and widths were extracted. Several regression methods, such as the least absolute shrinkage of selection operator (LASSO), random‐forest, gradient‐boosting, and extra‐tree were used to find the relationship between these descriptors and the Ead. The results show that the energy position of the peaks in the d‐projected DOS is the most important descriptor, in agreement with the previously known d‐band center theory. It was also shown that the peak position in d‐projected DOS improves the regression model in addition to the d‐band center, since it reduces the regression error. [ABSTRACT FROM AUTHOR]

The optical properties of bulk AuCu3-type ordered superconducting binary compounds ScGa3 and LuGa3 have been experimentally investigated for the first time in the wide spectral range and explained in terms of the band structure. First-principles calculations of electronic densities of states and optical conductivities are performed within the framework of LSDA+U method using the LMTO-ASA software package. The measured dielectric functions spectra for both materials exhibit a strong absorption region above ∼ 1 eV, which are in a reasonable agreement with the calculated metal-like energy structures of compounds. Features of quantum light absorption are discussed on the basis of a comparative analysis of experimental and theoretical spectra of interband optical conductivity. Plasma and relaxation frequencies of conduction electrons are determined. [ABSTRACT FROM AUTHOR]

Ultrafast control over the magnetic orientation of matter represents a vital element of potential future spin-based electronics ("spintronics"). While physical mechanisms underpinning spin switching are established for picosecond time scales, we here present a physical route to magnetization toggle control, i.e., multiple switching events, at <100 femtoseconds. A minority spin current injected into a ferromagnet is shown to generate rapid depopulation of the minority channel below the ground-state Fermi level, creating a minority "spin vacuum" that then drives rapid charge redistribution from the majority channel and spin switching. We demonstrate that this mechanism reproduces many of the features of recent subpicosecond switching of ferromagnetic Co/Pt multilayers and provide simple practical rules for the design of materials via tailoring the electronic density of states to optimize spin vacuum control over magnetic order. [ABSTRACT FROM AUTHOR]

The optical properties of bulk AuCu3-type ordered superconducting binary compounds ScGa3 and LuGa3 have been experimentally investigated for the first time in the wide spectral range and explained in terms of the band structure. First-principles calculations of electronic densities of states and optical conductivities are performed within the framework of LSDA+U method using the LMTO-ASA software package. The measured dielectric functions spectra for both materials exhibit a strong absorption region above ∼ 1 eV, which are in a reasonable agreement with the calculated metal-like energy structures of compounds. Features of quantum light absorption are discussed on the basis of a comparative analysis of experimental and theoretical spectra of interband optical conductivity. Plasma and relaxation frequencies of conduction electrons are determined. [ABSTRACT FROM AUTHOR]

CuCrZr alloy is widely used in vacuum circuit breaker contact materials and high‐speed railroad contact wires, etc. The study of the effect of different Cr and Zr contents on the performance of CuCrZr alloy is of great significance for the improvement of circuit breaker's breaking capacity, as well as the load and structural stability under harsh working conditions. In this paper, the mechanical properties, electronic density of states and thermodynamic properties of CuCrZr solid solution alloys randomly doped by different concentrations of Cr and Zr are comparatively analyzed using first‐principles calculations based on density functional theory. The results show that the alloys with different doping compositions have strong mechanical stability, electrical conductivity, and thermomechanical stability, and the reduction of the Cr/Zr doping concentration ratio can improve the toughness and ductility of the alloys, and the solid solution alloy with the composition of CuCr0.06Zr0.19 has the best machinability. The doping of Cr and Zr can improve the thermal stability of the alloy, Cr and Zr can be used as high‐temperature toughening elements for Cu. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Density functional theory calculations have been used to investigate the structural, electronic, and phonon dispersion properties of the V2PbC MAX phase. The materials space group remains unaltered after variable cells have been relaxed. Computed phonon results show that V2PbC is ductile and anisotropic. The electronic bands and density of states show metallic behaviour with impacts at and around the Fermi energy level originating mostly from the V-3D, Pb-6P, and C-2P orbitals. A set of phonon frequencies has been obtained by analyzing the forces connected to a systematic set of displacements. All phonon branches are positive, indicating that V2PbC is dynamically stable. [ABSTRACT FROM AUTHOR]

In this study, the superconductivity mechanism was theoretically examined by investigating the structural, electronic, elastic and phonon properties of the A15 type V3Ge compound using the Quantum Espresso package program, which deals with Density Functional Theory. Following the lattice constant calculations the bulk modulus and the first derivative of the bulk modulus with respect to pressure were with the help of energy values corresponding and different lattice constants and Murnaghan equations of state. Calculations regarding the electronic proerties were made using the Generalized Gradient Approach and Pseudopotential Method and as a result, the electronic band structure graphs of the V3Ge compound were prepared separately by including the spin-orbit interaction in the calculation and excluding the spin-orbit interaction. In addition, from the electronic density of states graph calculated for the V3Ge crystal, the density of states at the Fermi level, N(EF), which has an important place in the investigation of the superconductivity mechanism of the V3Ge crystal was calculated using full-relativistic ultrasoft pseudopotentials. Investigation of the elastic properties of superconducting materials is also very important for the theoretical understanding of superconductivity properties. Therefore, in this study, the elastic properties of the V3Ge compound are discussed in detail. Elastic constant values have been obtained by using the Stress-Strain method. In order to investigate the superconductivity properties of V3Ge, phonon properties should be analysed. As a result of the phonon calculations, the average phonon frequency and electron-phonon interaction parameter were obtained. These parameter values were used to reveal the critical temperature of the V3Ge compound for transition to superconductivity using the Migdal-Eliashberg approach. [ABSTRACT FROM AUTHOR]

Cerium compounds have invited enough attention from scientists and researchers with respect to practical and fundamental implications having exotic physical, electronic, and magnetic properties like the kondo effect, anisotropic magnetic order, giant Hall effect and superconductivity. Hereby, we describe the mechanical stability and present the electronic, structural, and magnetic properties of new silicon-doped alloys of Cerium Phosphide with generic formula CeSixP1-x (x=0, 0.25, 0.5, 0.75 and 1.0) by using Wien2k code through DFT formalism. The simulation employs generalized gradient approximation through Perdew Bruke Ernzerhof with spin mode. The computed variables are lattice constants, volume, bulk modulus, pressure derivatives, and energy for structural studies. The partial and total densities of states and electronic energy band structures are calculated for electronic studies of these compounds. The magnetic properties of these compounds are described by computing spin magnetic moments. These doped alloys are predicated on being structurally stable, metallic, and non-magnetic materials. [ABSTRACT FROM AUTHOR]

We investigated the impact of annealing on the structural characteristics and superconducting critical temperature ( T c ) of the eutectic high-entropy alloy (HEA) superconductor NbScTiZr. The HEA manifests an eutectic microstructure composed of body-centered cubic (bcc) and hexagonal close-packed phases. Both the lattice parameters of the bcc phase and grain size of the eutectic structure exhibited pronounced sensitivity to variations in annealing temperature. The observed dependence of the lattice parameter on annealing temperature supports the possibility that lattice strain occurs at lower annealing temperatures. The as-cast sample demonstrated superconductivity at T c of 7.9 K, which increased to 9 K after annealing at 800 ∘ C. However, when subjected to annealing at 1000 ∘ C, T c diminishes to 8.7 K. The annealing temperature dependence of T c cannot be comprehensively elucidated based solely on the electronic density of states at the Fermi level. It is plausible that the lattice strain may influence the annealing temperature dependence of T c . Our results for the critical current density J c reveal that the self-field J c of the as-cast NbScTiZr at 2 K exceeds 10 6 A/cm 2 . [ABSTRACT FROM AUTHOR]

Despite advances in mixed tin‐lead (Sn‐Pb) perovskite‐based solar cells, achieving both high‐efficiency and long‐term device stability remains a major challenge. Current device deficiencies stem partly from inefficient carrier transport, originating from defects and improper band energy alignment among the device's interfaces. Developing multifunctional interlayer materials simultaneously addressing the above concerns poses an excellent strategy. Herein, through molecular and crystal engineering, an amine‐functionalized C60 mono‐adduct derivative (C60‐2NH3 = bis(2‐aminoethyl) malonate‐C60) is utilized for the synthesis of the first crystalline fullerene‐based 2D metal halide semiconductor, namely (C60‐2NH3)Pb2I6. Single crystal XRD studies elucidated the structure of the new material, while DFT calculations highlighted the strong contribution of C60‐2NH3 to the electronic density of states of the conduction band of (C60‐2NH3)Pb2I6. Utilization of C60‐2NH3 as an interlayer between a FA0.6MA0.4Pb0.7Sn0.3I3 perovskite and a C60 layer offered superior band energy alignment, reduced nonradiative recombination, and enhanced carrier mobility. The corresponding perovskite solar cell (PSC) device achieved a power conversion efficiency (PCE) value of 21.64%, maintaining 90% of its initial efficiency, after being stored under a N2 atmosphere for 2400 h. This work sets the foundation for developing a new family of functional materials, namely Fullerene Metal Halide Semiconductors, targeting applications from photovoltaics to catalysis, transistors, and supercapacitors. [ABSTRACT FROM AUTHOR]

Metal–support interaction plays a critical role in determining the eventual catalytic activity of metals loaded on supporting substrates. This interaction can sometimes cause a significant drop in the metallic property of the loaded metal and, hence, a drop in catalytic activity in the reactions, especially in those for which low charge carrier transfer resistance is a necessary parameter. Therefore, there should be a case-by-case experimental or theoretical (or both) in-depth investigation to understand the role of support on each metal. Here, onto a layered porous carbon nitride (g-CN), we grew single crystalline Pt nanodisks (Pt@g-CN) with a lateral average size of 21 nm, followed by various characterisations such as electron microscopy techniques, and the measurement of electrocatalytic activity in the O2 reduction reaction (ORR). We found that intercalating Pt nanodisks in the g-CN interlayers causes an increase in electrocatalytic activity. We investigated the bonding mechanism between carbon support and platinum using density functional theory and applied the d-band theory to understand the catalytic performance. Analysis of Pt's density of states and electronic population across layers sheds light on the catalytic behaviour of Pt nanoparticles, particularly in relation to their thickness and proximity to the g-CN support interface. Our simulation reveals an optimum thickness of ~11 Å, under which the catalytic performance deteriorates. [ABSTRACT FROM AUTHOR]

Doping or partially substituting WC with metals, e.g., Mo and Cr, can lower its density while keeping the strength of the modified carbides similar to that of WC, making them attractive as the reinforcement for hardfacing overlays and tool steels, since they can be distributed homogeneously in the metal matrix. However, it is unclear if the doped WC has desirable interfacial bonding with the matrix, e.g., iron. In this study, we investigated the interfacial bonding of Mo- and Cr-doped WC, compared to that of mono-WC, with austenite and ferrite irons via first-principles calculations. (11 2 ¯ 0) C a r b i d e / / (110) F e , (10 1 ¯ 0) C a r b i d e / / (100) F e , and (0001) C a r b i d e / / (100) F e interfaces for both ferrite and austenite with the lowest interfacial mismatch were investigated. Characteristics of the formed interfacial bonds were studied based on the electron localization function, electronic density of states, bond order, and net charge. It was demonstrated that the Mo and Cr-doped WC carbides, (W4−x, M)C4, show comparable or higher adhesive work with iron, compared to that of mono-WC with iron. The metal-substituted or doped W4C4 carbides are promising replacements of heavier WC for tool steels and ferrous hardfacing overlays. [ABSTRACT FROM AUTHOR]

Using density functional theory calculation and rigid band model, we investigate the electronic structure and magnetostrictive properties of transition heavy-metal doped Fe-based (Fe–Al, Fe–Si, Fe–B, and Fe–Be) alloys. It is found that a small amount of addition of 4d/5d heavy-metal atoms greatly enhances the coefficient of tetragonal magnetostriction of Fe-based alloys, reaching up to about 1000 ppm in Fe87.5Al6.25Pt6.25 and Fe75Al18.75Rh6.25 alloys. The underlying mechanism is mainly ascribed to combined factors of band narrowing induced by non-bonded states in pure Fe layer, strong spin–orbit coupling effect by heavy metals, and improved mechanical properties, through analysis of the electronic density of states near Fermi level and k-mesh resolved magnetocrystalline anisotropy energy in momentum space. These results provide useful guidance for optimizing the magnetostrictive performance of Fe-based alloys for practical application. [ABSTRACT FROM AUTHOR]

We employ deep kernel learning electronic coarse-graining (DKL-ECG) with approximate Gaussian processes as a flexible and scalable framework for learning heteroscedastic electronic property distributions as a smooth function of coarse-grained (CG) configuration. The appropriateness of the Gaussian prior on predictive CG property distributions is justified as a function of CG model resolution by examining the statistics of target distributions. The certainties of predictive CG distributions are shown to be limited by CG model resolution with DKL-ECG predictive noise converging to the intrinsic physical noise induced by the CG mapping operator for multiple chemistries. Further analysis of the resolution dependence of learned CG property distributions allows for the identification of CG mapping operators that capture CG degrees of freedom with strong electron–phonon coupling. We further demonstrate the ability to construct the exact quantum chemical valence electronic density of states (EDOS), including behavior in the tails of the EDOS, from an entirely CG model by combining iterative Boltzmann inversion and DKL-ECG. DKL-ECG provides a means of learning CG distributions of all-atom properties that are traditionally "lost" in CG model development, introducing a promising methodological alternative to backmapping algorithms commonly employed to recover all-atom property distributions from CG simulations. [ABSTRACT FROM AUTHOR]

The experimental discovery of four-layer orthorhombic (4O) martensite has added new research motivation to the Ni–Mn–Sn magnetic shape memory alloy. Herein, the martensitic transformation, magnetic properties, and electronic structures of Ni2Mn1+xSn1−x alloys are investigated using the first-principles calculations. The results show that the increasing Mn content destabilizes the stability of austenite (A) compared to the non-modulated (NM) martensite. This composition adjustment promotes the occurrence of martensitic transformation in the range of 0.375 ≤ x ≤ 0.75, and the corresponding phase transition sequence is A → 4O → NM during cooling. An intense hybridization bond exists between excess Mn and its surrounding atoms. The increasing antiferromagnetic interaction between excess Mn and normal Mn weakens each atomic moment and, thus, the total magnetic moment. Furthermore, the physical essence of the phase stability and magnetic properties variation with composition was explained based on the electronic density of states. [ABSTRACT FROM AUTHOR]