Electronic Energy Bands Research Articles

Optimizing energy conversion in direct carbon fuel cells based on brown coal char: Exploring the impacts of scandium substituted La0.6Sr0.4FeO3-δ anodes

Direct coal fuel cells (DCFCs) convert the chemical energy in coal directly into electricity, but their development has been hindered by insufficiently active anode materials and slow carbon oxidation kinetics. This study explores the use of scandium-doped B-site-deficient La0.6Sr0.4FeO3-δ (LSFScx, x = 0, 0.05, 0.10, 0.15) as anodes for brown coal char utilization in DCFCs. Our findings show that LSFScx (x≠0) anodes outperform the undoped LSF anode, with the LSFSc0.1 anode exhibiting the best performance. At 850 °C, the LSFSc0.1 anode achieves a maximum power density of 345.5 mW cm−2, a minimum polarization resistance of 0.18 Ω cm2, and an impressive discharge time of 13.23 h. These enhancements are attributed to scandium doping, which improves the three-phase reaction boundaries, enhances carbon oxidation through better oxide ion transport, and optimizes the electronic structure. Theoretical calculations indicate that scandium doping reduces the Bader charges of Fe atoms, weakens OFe bonds, lowers the oxygen vacancy formation energy, and maintains the electronic energy band structures. These results provide a new and effective pathway to improve the anode performance and efficiency of DCFCs, showcasing new possibilities for future research on scandium-based perovskite materials for DCFC applications.

Investigating the adaptability of CsMF3 (M = Ge, Si) perovskites under hydrostatic pressure for improved optoelectronic performance: A DFT-based computational study

The Cesium-based halide perovskites CsMF3 (M = Ge, Si) were examined in detail, using density functional theory evaluated ab-initio calculations, under hydrostatic pressures varying between 0 and 40 GPa. The structural, electronic, bonding, optical, anisotropic elastic, and mechanical characteristics of prospective photovoltaic materials are examined to assess their viability. The structural, thermodynamical, mechanical, and vibrational stabilities are validated through the analysis of the Goldschmidt tolerance factor, formation energy, Born stability criteria, and phonon calculations, respectively. Both the GGA-PBE model and the non-local hybrid sX potential were utilized to estimate the structural parameters and electronic energy band gaps. The calculated band gaps indicate that the compounds exhibit semiconductor behavior at ambient pressure with values 2.074 eV (2.642 eV) for CsGeF3, and 1.097 eV (0.977 eV) for CsSiF3 utilizing GGA-PBE (hybrid sX) potential. However, increased pressure reduces the band gap, resulting in enhanced conductivity and causing a shift from a semiconductor to a metallic state. The charge density map distinguishes between the ionic character of the Cs-F bond and the covalent nature of the Ge/Si-F bond. When pressure is applied, the bond strength increases, leading to a uniform decrease in bond length. The application of pressure also improves the optical functionalities, suggesting that these materials could be effectively utilized in various optoelectronic devices designed for the visible and ultraviolet spectra. In addition, hydrostatic pressure has a significant influence on the mechanical characteristics while retaining stability. Under pressure, both the ductile and anisotropic characteristics become more prominent for CsMF3 (M = Ge, Si) solids.

Effects of La/Mn-Ceria&TiO2 heterojunction on titanium implants: Improved regenerative repair of diabetic bone with enhanced antioxidant characteristics

Hyperglycemia-induced oxidative stress (OS) plays a crucial role in implant osseointegration and often results in implant failure in patients with diabetes. Implants modified with cerium nanoparticles (CeO2-NPs) have gained significant attention owing to their remarkable oxidase-mimetic activity and therapeutic potential. Increasing the Ce3+ content and oxygen vacancy concentration in CeO2-NPs enhances the catalytic activity of CeO2-NPs. In this study, we synthesized lanthanide (La)/manganese (Mn) -doped CeO2-NPs composite coatings (La-CNPs and Mn-CNPs) on alkali-etched Ti substrates using a one-step hydrothermal method. Our findings indicate that the integration of La/Mn doping, in conjunction with a titanium dioxide carrier, augmented both the Ce3+ content and the oxygen vacancy concentration in La-CNPs and Mn-CNPs. By analyzing their electronic energy band structures, we found that La-CNPs exhibited superior catalase activity, whereas Mn-CNPs outperformed them in terms of superoxide dismutase activity. Under OS conditions, La-CNPs and Mn-CNPs (especially Mn-CNPs) markedly reduced intracellular reactive oxygen species levels in MC3T3-E1 cells, promoting their proliferation and osteogenic differentiation. Complementing these in vitro observations, in vivo trials underscored the capability of Mn-CNPs to enhance osteointegration in surrounding implants in diabetic rat models. Consequently, Mn-CNPs coatings present a promising avenue for augmenting the efficacy of implant therapies, especially in patients with diabetes.

Effect of rare earth ions on the optical and electronic properties of defect chalcopyrite: Experimental and theoretical investigation

The present research is a systematic experimental and computational study focused on structural, electronic, and optical properties of ZnGa2S4 doped with neodymium rare earth ions for the first time. High-intensity, narrow-band luminescence peaks are observed in the visible and infrared regions by doping the matrix with Nd ions. These peaks in the background of the broadband spectrum are due to intercenter 4f-4f transitions of Nd3+ ions. The fact that the Raman peaks of the alloy crystal are more intense than that of the pure crystal confirms that the neodymium does not move freely in the lattice and occupies the place of defects. This confirms the results from our X-ray structural analysis. The crystal lattice parameters of the studied materials were determined as follows: a = 5.496 Å, c = 10.99 Å, c/a = 2. To explain the electronic, optical and magnetic properties, using ATK-DFT method, electronic energy band structure, density of states and optical spectrum for pure and doped with ZnGa2S4:Nd compound are computed and discussed. DFT result shows that impurity Nd leads to a decreased bandgap of ZnGa2S4 due to the hybridization of Nd-4d with S-3p orbital in the forbidden gap. The peaks in the optical spectrum are shifted toward the lower energy range for doped supercell.

Synergistic interaction of S-type heterojunction and sulfur vacancies in g-C3N5@Sv-ZnIn2S4 composites: Simultaneous promotion of complete 2,4-dichlorophenol mineralization and Cr(VI) reduction

Constructing efficient heterojunction photocatalysts is an effective measure for degrading pesticides and reducing heavy metals. In this study, g-C3N5@Sv-ZnIn2S4 (g-C3N5@Sv-ZIS) composite with large specific surface area has been successfully prepared by a simple low-temperature water bath method. The g-C3N5@Sv-ZIS composite showed complete mineralization of 2,4-dichlorophenol (2,4-DCP) and reduction of Cr(VI) within 60 min. The results of electron spin resonance spectroscopy, photoelectrochemical characterization, and energy band structure calculations indicated the formation of an S-type heterojunction at the interface of g-C3N5 and Sv-ZIS. In situ XPS analysis showed the transfer of photogenerated charges from g-C3N5 to Sv-ZIS. The molecular structure of 2,4-DCP was analyzed using frontier molecular orbital and electrostatic potential calculations. The possible degradation pathways of 2,4-DCP were proposed based on liquid chromatography– mass spectrometry results. Biotoxicity simulations of the intermediates revealed decreased toxicities. Furthermore, The kinetic rate constant of CZSv-200 for degrading 2,4-DCP and Cr(Ⅵ) in deionized water was approximately 2.20, 3.10 and 2.46, 4.03 times higher than that in lake and sewage plant water, respectively. The composites designed in this study provide reliable theoretical support for the removal of composite pollutants.

Quasi-Dirac points in electron-energy spectra of crystals

Specific properties, such as surface Fermi arcs, features of quantum oscillations and of various responses to a magnetic field, distinguish Dirac semimetals from ordinary materials. These properties are determined by Dirac points at which a contact of two electron-energy bands occurs and in the vicinity of which these bands disperse linearly in the quasimomentum. This work shows that almost the same properties are inherent in a wider class of materials in which the Dirac spectrum can have a noticeable gap comparable with the Fermi energy. In other words, the degeneracy of the bands at the point and their linear dispersion are not necessary for the existence of these properties. The only sufficient condition is the following: In the vicinity of such a quasi-Dirac point, the two close bands are well described by a two-band model that takes into account the strong spin-orbit interaction. To illustrate the results, the spectrum of ZrTe5 is considered. This spectrum contains a special quasi-Dirac point, similar to that in bismuth.

Construction of ZnAl LDH-Derived Sulfides with Etching Modification to Trigger Photocatalytic H2 Production and Degradation Oxidation.

Constructing novel functional photocatalysts represents a promising approach to optimize the energy band structure and facilitate the separation of photogenerated carriers. Layered double hydroxides (LDHs) exhibit notable advantages in photocatalysis due to the exceptional photoelectrochemical properties and elevated number of active surface atoms. However, an unsuitable band gap and limited carrier migration have inhibited their development in photocatalysis. Herein, we propose a novel in situ topological vulcanization strategy for optimizing the photocatalytic activity of ZnAl LDH-derived sulfides (ZnAlSx). The subsequent etching process via a 1 M NaOH solution was introduced to construct the ZnSx photocatalysts. Then, the crystallinity of the crystals was enhanced by etching to further improve the catalytic activity and stability of ZnSx. The as-synthesized ZnSx shows an excellent photocatalytic hydrogen production rate (11.89 mmol/g/h) and tetracycline degradation efficiency (91.94%) under light illumination, and its hydrogen evolution efficiency is approximately 176 and 2 times greater than that of ZnAl LDH and ZnAlSx, respectively. The characterization and density functional theory (DFT) analysis confirmed that the surface electronic properties and energy band structure of ZnAl LDH were significantly optimized after experimental treatment, resulting in enhanced carrier separation and photooxidative reduction capacity. Combining in situ topological vulcanization and etching to realize the functional conversion of ZnAl LDH provides promising insights into the construction of high-performance, low-cost photocatalysts.

First-principles investigation of electronic, structural, and magnetic properties of Si substituted cerium phosphide compounds CeSixP1-x

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.

Effect of Cr doping on electronic and optical properties of mono/bilayer MoTe2 nanosheets– a first-principles study

The influence of Cr-doping on mono/bilayer MoTe2 nanostructures is studied within the framework of density functional theory (DFT) since doping may be used to effectively tailor the electronic and optical characteristics in a desired manner. Chromium (Cr) seems to modify the electronic properties and energy band gap of MoTe2 considerably. At first, we confirmed the stability of the proposed structure with the support of cohesive formation energy and phonon-band-spectrum. Moreover, doping with Cr on MoTe2 produces a red shift towards far infra-red region in the absorption coefficient, thus making it suitable for far infra-red region applications. Hence, Cr doping is employed in this work. When Cr impurities are substituted in pristine MoTe2 nanostructures, the band structure gets modified. Additionally, the band gap of mono/bilayer MoTe2 nanostructures reduces from 1.143/0.74 eV for pristine MoTe2 to 0.807/0.621 eV for 8 % substitution of Cr. By examining absorption spectra, it was found that the optical characteristics of mono/bilayer MoTe2 changed significantly with doping of Cr impurities. The results of this study provide insight into the band structure, optical, and electronic attributes of mono/bilayer MoTe2 nanostructures that could be further fine-tuned for optoelectronic applications using substitution of Cr impurities.

Oxygen vacancy-mediated activation of Zn-O bonds at the S-scheme heterostructure interface for efficient uranium collection and resistance to biological contamination

Efficient reduction of U(VI) to U(IV) during seawater uranium extraction remains a challenge. Here, cerium dioxide quantum dots were bonded to the surface of indium zinc sulfide (ZIS) to form ZIS composite cerium dioxide quantum dots (ZIS/QDs-Ce). The oxygen vacancies are able to activate the Zn-O bonds at the ZIS and QDs-Ce interfaces, thus enabling the constructed S-scheme heterojunction to show great potential in facilitating the separation and transfer of photogenerated carriers. ZIS/QDs-Ce exhibited high anti-bio-pollution activity by generating biotoxic free radical reactive oxygen species (ROS). The photo-induced reduction of uranium by ZIS/QDs-Ce in 10 ppm uranium spiked simulated seawater reached 99.6 %. Oxygen vacancies cause distortions in the crystal field, and the Zn-O bond activation process triggers the movement of ZIS/QDs-Ce from the singlet low-spin state to the stable triplet state, resulting in free-carrier trapping centers and optimized electronic energy band structures. ZIS/QD-Ce has superior uranium extraction capabilities and is highly recommended for uranium extraction from seawater.

Multiferroicity in a two-dimensional vanadium dioxide

Two-dimensional (2D) multiferroic materials have attracted great interest owing to the integration of ferroelastic and ferromagnetic properties. We identify a novel 2D multiferroic vanadium dioxide (VO₂) monolayer exhibiting a monoclinic phase with a C2/m space group using density functional theory (DFT) calculations. The energetic, dynamic, thermodynamic and mechanical analyses indicate that the monolayer exhibits excellent stability and can be prepared experimentally. The arrangement of the electronic energy bands is analogous to that of a type I heterostructure. The electron doping at a concentration of 0.2 electrons per V atom results in a significant increase in the Curie temperature (TC) from 11.2 to 184 K estimated by Monte Carlo simulations, and a transition from semiconductor to half-metallicity. In addition, the VO₂ monolayer exhibits 120° ferroelastic switching with a moderate switching energy barrier of 32 meV per atom, subsequently allowing 120° rotation of the easy magnetisation axis. Our work reveals the intrinsic multiferroicity of VO₂, which may provide a guidance on the design of next-generation mechanical/spintronic devices.

Recycling of UO22+ expanded by metal-organic framework bearing pyrazinoquinoxaline tetracarboxylic acid: pH fluorescence sensing and photocatalytic activity

With the wide application of nuclear energy, the recycling of uranium resources and environmental protection have become the focus of scientific research and industrial attention. Uranyl ions have better electronic configurations and optical properties, but poor energy utilization and recycling as ionic states. Drawing on the structural features of Metal-Organic Frameworks (MOFs), the combination of UO22+ nodes with photoactive ligands should be able to effectively regulate the energy level matching between metal nodes and conjugated ligands, improve the electronic configuration and energy band structure, and thus produce better photoresponsive functional properties. In the present work, an example of a novel two-dimensional layered U-MOF was constructed by self-assembly, which utilizes pyrazinoquinoxaline tetracarboxylic acid. Due to the stable coordination structure, matched energy levels and synergistic photoresponsive behavior of UO22+ with pyrazinoquinoxaline ligands, U-MOF enables fluorescence sensing response in aqueous solution at pH=2–5, 9.5–12 and fluorescence quenching detection of a wide range of substrates. Theoretical calculations reveal that the interaction of the hydrogen ion with pyrazinozinoquinoxaline moiety extends the degree of conjugation of the moiety. Meanwhile, the interaction of hydroxide ions with pyrazinozinoquinoxaline groups elevates the highest occupied molecular orbital (HOMO) energy level, which significantly affects the photoelectric properties of U-MOF. In addition, U-MOF can be used as a photocatalyst to realize the conversion of benzylamine to N-benzylbenzylideneimine by oxidation under mild conditions. The effective electron transfer between uranyl ions and ligands ensured the photogenerated electron-hole separation efficiency and enhanced the energy utilization. Therefore, the related results of U-MOFs illustrate the practicality of introducing UO22+ nodes into MOFs to construct novel photoresponsive materials, which provides a new way for the efficient recycling and utilization of uranium resources.

Exploring interlayer coupling in the twisted bilayer PtTe2

We have investigated interlayer interactions in the bilayer PtTe2 system, which influence the electronic energy bands near the Fermi level. Our diffusion Monte Carlo (DMC) calculations for the high-symmetry bilayer stackings (AA, AB, AC) manifest distinct interlayer binding characteristics among the stacking modes by revealing significantly different interlayer separations depending on the stacking, which is critical to understanding the interlayer coupling of the twisted bilayers consisting of various local stacking arrangements. Furthermore, a comparison between the interlayer separations obtained from DMC and density functional theory (DFT) shows that meta-generalized gradient approximation (GGA)-based van der Waals–DFT results agree with DMC for different layer stackings, including twisted bilayers, but only the ground-state AA stacking matches well with GGA-based DFT predictions. This underscores the importance of accurate exchange-correlation potentials even for capturing the stacking-dependent interlayer binding properties. We further show that the variability in DFT-predicted interlayer separations is responsible for the large discrepancy of band structures in the 21.79∘ twisted bilayer PtTe2, affecting its classification as metallic or insulating. These results demonstrate the importance of obtaining a correct description of stacking-dependent interlayer coupling in modeling delicate bilayer systems at finite twists. Published by the American Physical Society 2024

Tuning of Band Gap of Cathode Li2NiPO4F by Replacing P to Nb and Forming Li2NiNbO4F for Application as 5 V Cathode in Lithium Ion Battery: A Density Functional Theory Study

Electrochemical properties of Li2NiPO4F were studied using density functional theory. The obtained voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density are achieved as 5.33 V, 4.0 eV, 287.3 mAh g−1 and 1531.31 Wh kg−1, respectively. Although, the electrochemical properties of Li2NiPO4F are promising, large electronic band gap would certainly pose a limitation for its commercial application. Nb is a transition metal and its electronegativity is 1.6 which is less than the electronegativity of 2.19 for P. This implies, less operating voltage would be obtained if we replace P in Li2NiPO4F by Nb to form Li2NiNbO4F. However, electronic configuration of Nb is [Kr] 4d45 s1 and the valance state of Nb in Li2NiNbO4F is +5, which in turn specify that, localized Nb d states will reside in conduction band of Li2NiNbO4F and hence the electronic band-gap would be less owing to this localized Nb-d states. Our speculation gets verified by the calculated properties of Li2NiNbO4F obtained through DFT as follows; Voltage, electronic band gap, capacity (∼ for 2 Li+ extraction) and energy density achieved, respectively, are 5.01 V, 3.64 eV (less than LiFePO4), 215.71 mAh g−1, 1080.71 Wh kg−1. Lower electronic band gap of Li2NiNbO4F makes it an alternative to Li2NiPO4F.

Unraveling the nature of local field distortion-induced dual electron-trapping centers for efficient photocatalytic fuel evolution

Active electron-trapping centers play significant roles in photocatalysis. Herein, we synergize local field distortion and defects in nanocrystals to produce dual electron-trapping centers and unravel the nature of aluminum doping in porous ZnO with tunable amounts of heteroatoms and oxygen vacancies. The introduced Al atoms in the structural domain induce local field distortion and trigger the movement of Zn2+ from a singlet low spin state to a stable triplet state, resulting in the generation of free carriers trapping centers and optimized electronic energy band structure. Dual active electron-trapping centers of heteroatoms and oxygen vacancies promote the Separation of photo-generated charge carriers and reduce the adsorption energies of H* species. Furthermore, the d-band center of Al-doped ZnO with oxygen vacancies shifts to a higher energy position, thus promoting the adsorption and desorption of hydrogen intermediates and exhibiting 4-fold the photocatalytic H2 efficiency of pristine ZnO. This study provides new insights into the rational design of highly efficient oxide-based photocatalysts toward sustainable solar fuel evolution.

Graphitic carbon nitride sheets sandwiched metal oxides: A novel platform for S-Scheme heterojunction generation for efficient photodegradation of volatile organics

This study reports the preparation of new kind of S-Scheme heterojunction (SSHJ) photocatalyst by distributing two semiconducting metal oxides (titanium dioxide and ZnO) onto the surface of graphitic carbon nitride (G-CN) two dimensional (2D) sheets. The composite photocatalysts, designated as T/Z@ GCN SSHJ, were prepared with different mass ratios of T,Z and G-CN.X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM), field emission scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy were used to characterize the microstructure, morphology, chemical composition, electronic states, and optical properties of the T/Z@ GCN SSHJ composite. TEM image of the typical T/Z@ GCN SSHJ composite shows the presence of distribution of particles with sizes in the range 40–80 nm on the lamellar surface of G-CN inferring the formation of a heterostructure Z(0 D) /G-CN(2D)/T(0D) SSHJ composite. The comparison of the core level XPS spectrum of Ti 2p, Zn 2p, C1s, O1s and N1s of T/Z@ GCNSSHJ composite with the binary composites (T+G-CN and Z+G-CN) and pristine components clearly suggests that that Z, T and G-CN are kept together through van der Walls interactions. The T/Z@ GCN SSHJ composite photocatalyst with T: Z: G-CN mass ratio of 1.0: 0.80: 0.12 exhibited enhanced photocatalytic degradation (%) over binary and pristine single components for all the tested volatile organic compounds (VOCs), namely, acetaldehyde (ACD), ethyl acetate (EA), toluene (T) and benzaldehyde (BA). On comparing the % removal of VOCs after 20 minute of light irradiation, BA showed the highest removal % (94.3 %) and the others take the following order: ACD (70.9 %) >EA (56.45 %)> TL (40.12 %). The study explains the enhanced performance of T/Z@ G-CN HJ composite towards VOC photodegradation in terms of S-Scheme based charge transfer and internal electric field driven efficient charge separation. The charge transfer process of T/Z@ GCN HJ composite photocatalysts is discussed through S-Scheme HJ formation and supported with electronic states and band energy levels of the constituent components derived through the results of XPS and DRS analysis. This study gives insight into the design for regulating the hetero-interfaces for enhancing the photocatalysis and expected to further understand into charge transfer mechanism at multi-junction-based photocatalysts.

DFT+U study of TlXBr3 (X = Sn, Ge) perovskites as next-generation materials for optoelectronics applications

The lead-free perovskite has gained increasing importance in optoelectronic device applications. In this study, we investigate the structural, electronic, optical, mechanical, thermodynamic, and thermoelectric properties of cubic phase TlSnBr3 and TlGeBr3 using the plane wave pseudopotential method based on density functional theory (DFT). To overcome constraints of the GGA-PBE technique, we implemented the LDA + U technique to solve on-site self-interaction errors. The Hubbard parameter 'U' was identified as a suitable solution for considering on-site self-interactions and calculating better electronic energy band gaps. The obtained lattice parameters are consistent with previous published results. Our findings indicate that both materials have a direct energy band gap, with values of 1.75 eV and 1.94 eV for TlSnBr3 and TlGeBr3, respectively. We also observe the existence of covalent and ionic bonding. The optical properties of these materials demonstrate high absorption coefficients and conductivity in the visible region. The mechanical properties are derived using the Voigt-Reuss-Hill approximation and suggest strong evidence of ductile behavior. Finally, the thermoelectric properties are evaluated by analyzing thermal to electrical conductivity, Seebeck coefficient, and Figure of merit criteria. Our comparative study of TlXBr3 (X = Sn, Ge) suggests that these compounds are promising candidate materials for photovoltaic and optoelectronic devices.

Impact of Electron-Phonon Coupling on Graphene Intercalation Compounds from Self Energy: Polynomial Models Selection

In our pursuit of understanding electron-phonon coupling (EPC) and their impact on material properties, we delved deep into the intricate role played by the Eliashberg function in governing electron self-energy. Through meticulous evaluation of tailored polynomial models approximating this function, we unearthed profound insights into how phonon interactions intricately modify electronic energy bands. Employing numerical computations, we meticulously unraveled both the real and imaginary aspects of electron self-energy, crucial in comprehending EPC effects in various materials. Investigating superconductivity within monolayer graphene and its interaction with diverse doping substances, our study led us to identify optimal polynomial models that accurately capture EPC behaviors, offering invaluable implications for predicting critical temperatures in superconducting materials. Expanding the parameters within our models allowed us to anticipate changes in self-energy models for higher-order configurations not explored in this study. Our selection of polynomial spanning degrees from n = 1 to 10 the efficacy of n = 2 (Debye) as the most realistic and accurate model, closely followed by n = 1, albeit occasional deviations observed in specific materials. These discrepancies often stemmed from noise model inaccuracies and parameter approximations. Our comprehensive approach outshone the traditional Kramer-Kronig transform in assessing electron-phonon interactions. Looking ahead, the application of multiple models to the Eliashberg function diagram holds immense promise for enhancing accuracy, despite the challenge of concurrently adjusting multiple input parameters. This integration of numerical modeling with experimental data forms a robust framework, empowering the prediction and fine-tuning of material properties vital for the future fabrication of devices. HIGHLIGHTS Exploring the use of polynomial models to approximate the Eliashberg function, enabling a detailed analysis of electron-phonon coupling (EPC) in materials. Confirm the Debye model's accuracy in predicting the electronic structure of doped graphene. The findings suggest enhanced EPC in materials like CaC6 and its potential to induce superconductivity in monolayer graphene. This work offers a framework for future research and applications in superconducting materials using ARPES data. GRAPHICAL ABSTRACT

Spectral Analysis of Proton Eigenfunctions in Crystalline Environments

The Schrödinger equation and Bloch theorem are applied to examine a system of protons confined within a periodic potential, accounting for deviations from ideal harmonic behavior due to real-world conditions like truncated and non-quadratic potentials, in both one-dimensional and three-dimensional scenarios. Numerical computation of the energy spectrum of bound eigenfunctions in both cases reveals intriguing structures, including bound states with degeneracy matching the site number Nw, reminiscent of a finite harmonic oscillator spectrum. In contrast to electronic energy bands, the proton system displays a greater number of possible bound states due to the significant mass of protons. Extending previous research, this study rigorously determines the constraints on the energy gap and oscillation amplitude of the previously identified coherent states. The deviations in energy level spacing identified in the computed spectrum, leading to the minor splitting of electromagnetic modes, are analyzed and found not to hinder the onset of coherence. Finally, a more precise value of the energy gap is determined for the proton coherent states, ensuring their stability against thermal decoherence up to the melting temperature of the hosting metal.

Boosting energy levels in graphene magnetic quantum dots through magnetic flux and inhomogeneous gap

We study the effects of a magnetic flux and an inhomogeneous gap on the energy spectrum of graphene magnetic quantum dots (GMQDs). By considering the Dirac equation in the infinite mass framework, we can analytically obtain eigenspinor expressions. By applying boundary conditions, we obtain an energy spectrum equation in terms of system parameters such as radius, magnetic field, energy, flux, and gap. In the infinite limit, we recover Landau levels for graphene in a magnetic field. We show that the energy spectrum increases significantly in the presence of flux and a gap inside the GMQDs, which prolongs the lifetime of the trapped electron states. We show that higher flux also produces new Landau levels of negative angular momentum. Meanwhile, we find that the gap increases the separation between the electron and hole energy bands. As shown in the radial probability analysis, flux and gap emerge as influential factors in controlling electron mobility, affecting confinement, and prolonging the presence of quasi-bound states.