Study Of Electronic Structure Research Articles

Strong-field photoelectron holography in the subcycle limit

Strong-field photoelectron holography is promising for the study of electron dynamics and structure in atoms and molecules, with superior spatiotemporal resolution compared to conventional electron and X-ray diffractometry. However, the application of strong-field photoelectron holography has been hindered by inter-cycle interference from multicycle fields. Here, we address this challenge by employing a near-single-cycle field to suppress the inter-cycle interference. We observed and separated two distinct holographic patterns for the first time. Our measurements allow us not only to identify the Gouy phase effect on electron wavepackets and holographic patterns but also to correctly extract the internuclear separation of the target molecule from the holographic pattern. Our work leads to a leap jump from theory to application in the field of strong-field photoelectron holography-based ultrafast imaging of molecular structures.

First principles study of electronic structure and transport in graphene grain boundaries

Grain boundaries play a major role for electron transport in graphene sheets grown by chemical vapor deposition. Here we investigate the electronic structure and transport properties of idealized graphene grain boundaries (GBs) in bi-crystals using first principles density functional theory (DFT) and non-equilibrium Greens functions. We generated 150 different grain boundaries using an automated workflow where their geometry is relaxed with DFT. We find that the GBs generally show a quasi-1D bandstructure along the GB. We group the GBs in four classes based on their conductive properties: transparent, opaque, insulating, and spin-polarizing and show how this is related to angular mismatch, quantum mechanical interference, and out-of-plane buckling. Especially, we find that spin-polarization in the GB correlates with out-of-plane buckling. We further investigate the characteristics of these classes in simulated scanning tunnelling spectroscopy and diffusive transport along the GB which demonstrate how current can be guided along the GB.

A Janus carbaporphyrin pseudo-dimer

Carbaporphyrin dimers, investigated for their distinctive electronic structures and exceptional properties, have predominantly consisted of systems containing identical subunits. This study addresses the associated knowledge gap by focusing on asymmetric carbaporphyrin dimers with Janus-like characteristics. The synthesis of a Janus-type carbaporphyrin pseudo-dimer 5 is presented. It displays antiaromatic characteristics on the fused side and nonaromatic behavior on the unfused side. A newly synthesized tetraphenylene (TPE) linked bis-dibenzihomoporphyrin 8 and a previously reported dibenzo[g,p]chrysene (DBC) linked bis-dicarbacorrole 9 were prepared as controls. Comprehensive analyses, including 1H NMR spectral studies, single crystal X-ray diffraction analyses, and DFT calculations, validate the mixed character of 5. A further feature of the Janus pseudo-dimer 5 is that it may be transformed into a heterometallic complex, with one side coordinating a Cu(III) center and the other stabilizing a BODIPY complex. This disparate regiochemical reactivity underscores the potential of carbaporphyrin dimers as versatile frameworks, with electronic features and site-specific coordination chemistry controlled through asymmetry. These findings position carbaporphyrin dimers as promising candidates for advances in electronic structure studies, coordination chemistry, materials science, and beyond.

Investigations of swift heavy ion induced thermoluminescence effect, trapping parameter analysis, and density functional theory of MgB4O7: Eu phosphor

The present work reports swift heavy ion (SHI) induced thermoluminescence (TL) dosimetric properties and density functional theory (DFT) studies of Eu doped MgB4O7 phosphor. Comparative investigations of structural, and luminescent properties of MgB4O7:Eu phosphor upon irradiation by 100 MeV Ag7+ and Ni7+ ion beams at the varied fluence range from 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2 are presented systematically. Eu doped MgB4O7 phosphor is prepared by facile hydrothermal method. X-ray diffraction pattern of the material reveals its orthorhombic structure with crystallite size of ∼30 nm. Fourier transform infrared spectroscopy (FTIR) studies demonstrate loss of crystallinity of material after the SHI irradiations. Correlation of stopping powers and projectile range calculations is performed using SRIM software. The investigated photoluminescence properties show emission bands located in the orange-red region with prominent peaks centered at ∼593 nm and ∼625 nm corresponding to 5D0→7F1 and 5D0→7F2 transitions of Eu3+ion. The influence of ion beam fluence on the photoluminescence properties has been explored. Variation in the intensity of the PL peaks without any shift in the peak positions is observed at different ion fluence. The TL glow curve of phosphor exhibits two major dosimetric peaks (a) at 185 °C and 275 °C and (b) at 172 °C and 273 °C upon Ag7+ and Ni7+ ion beam irradiation respectively. The phosphor shows fairly good linear dose response in the range of 1 × 1010 ion/cm2 to 5 × 1012 ion/cm2. Fading measurements reveal 10% and 12% fading for the irradiation of Ag7+ and Ni7+ ions respectively in two months. Trapping parameter calculations of SHI irradiated phosphors are carried out via various TL glow curve analysis methods such as, peak shape method, whole glow peak method, and glow curve deconvolution method. Efficient thermoluminescence properties of MgB4O7:Eu make it a potential phosphor material and promise to provide avenue into swift heavy ion dosimetry applications. DFT computational studies performed to obtain the electronic structure of Eu doped MgB4O7 phosphor support the experimental results of crystal structure, symmetry and electronic structure studies.

First-Principles Calculations to Investigate Spin-Oriented Magnetic Phases, Band Gaps, Elastic, and Thermodynamic Calculations of VNi2O4

In this study, spin and U-Coulomb interactions-dependent electronic structure, pressure-dependent elastic, and thermodynamics studies of VNi2O4 were performed. The ferromagnetic (FM) phase was the most stable magnetic phase. The lattice parameter was calculated as 8.32 Å. The bulk modules were calculated as 197.695 GPa and 198.038 GPa, respectively, in the initial condition and the elastic calculations, so the initial and elastic conditions were compatible. VNi2O4 material had band gaps of 1.597 eV, 2.159 eV, 2.659 eV, 3.094 eV, 3.439 eV, 3.729 eV, and 3.978 eV in the majority spin electrons in the Generalized Gradient Approximation (GGA), and U-Coulomb interactions (U = 1, 2, 3, 4, 5 and 6 eV), respectively. Hence, it was a true half-metallic ferromagnetic. VNi2O4 was ductile at 0 GPa, with a Debye temperature of 586.596 K. The net magnetic moment of VNi2O4 was 6.00 µB/f.u. As a result, VNi2O4 provides all the necessary conditions for spintronic applications.

NiO surface reduction by Nd overlayers

Metal/metal oxide interfaces have significant impact on modern technologies like microelectronics, solar cells, magnetic storage, and sensors due to their distinct electronic and structural properties. Such interfaces sometimes deviate from ideal bulk-termination which influences the system's overall performance. Here, we present the study of the interfacial electronic structure formed by the deposition of Nd layers onto NiO thin films utilizing X-ray photoelectron spectroscopy (XPS) and Ultraviolet photoemission spectroscopy (UPS). Our study indicates that the interface between the rare earth metal (Nd) and NiO differs from the ideal sharp interface. The portion of NiO surface reduced to metallic Ni while the deposited Nd metal is oxidized, indicating the interfacial oxidation/reduction process. The thickness of this interfacial Ni layer increases with increase in Nd metal deposited and reaches maximum depth of 3.0 Å when effective Nd overlayer thickness reaches 7.9 Å. Such an interface reaction could be utilized in heterostructures where an intentional reduction of the oxides is desired.

Study of electronic structure, elastic and thermodynamic properties of Cu2MgSnS4 under different pressures

The electronic structure, elastic and thermodynamic properties of Cu2MgSnS4 was studied based on density functional theory (DFT). The results show that Cu2MgSnS4 is a direct bandgap semiconductor. The B/G of Cu2MgSnS4 is greater than 1.75, indicating that Cu2MgSnS4 is a ductile material. Through the study of thermodynamic properties, it is found that the temperature increases, the bulk modulus B and Debye temperature Θ decrease, while the heat capacity CV, entropy S, Grüneisen constant γ and thermal expansion coefficient α increase, and the heat capacity is close to the Dulong-Petit limit. As the pressure increases, the bulk modulus B, Debye temperature Θ increases, while the entropy S, Grüneisen constant γ and heat capacity CV decrease.

DFT study of Atomic and electronic structures of trans-vacant 1M Al-rich illite

DFT study of Atomic and electronic structures of <i>trans</i>-vacant 1<i>M</i> Al-rich illite

The study of electronic structure and magnetic properties of ferromagnetic Kondo-lattice CePd2P2 from the first-principles

The electronic structure of ferromagnetic CePd2P2 Kondo lattice crystallizing in the tetragonal ThCr2Si2-type structure is investigated by means of the Density Functional Theory (DFT) and Time-Depedent DFT (TDDFT) methods. The calculated electronic properties from DFT are presented and compared to those of the non-magnetic LaPd2P2 compound. The differences in the FS topologies upon changing magnetic states (paramagnetic → ferromagnetic) is also examined. Including the relativistic effects of without or with spin-orbit coupling, and Hubbard corrections in the calculations, ferromagnetic ground state with an ordered magnetic moment of ∼ 0.8-0.9 μB is corroborated. Meaningful changes in the magnetic moment and electronic properties of CePd2P2 are discussed in terms of effects brought by the Coulomb interaction (U), and the Hund coupling (J). In particular, the reduction in magnetic moment and simultaneously enhancement of DOS at the Fermi energy due to decreasing J are in quantitative concordance with the Kondo lattice characteristic. Furthermore, dynamical model used in TDDFT calculations exhibits that 4 f electrons in CePd2P2 tend to be delocalized. The frequency-temperature behavior of response function allows to estimate the Kondo temperature to amount 19 K.

First-Principles Study of Electronic Structure and Optical Properties of Ni-Doped Bi4O5Br2

In this study, we comprehensively explored the electronic structure and optical properties of Ni-doped Bi4O5Br2 through first-principles computational calculations. By calculating its electronic structure and band characteristics, we investigated the impact of Ni doping on the photocatalytic performance of Bi4O5Br2. The computational results indicated that Ni doping significantly altered the band structure of Bi4O5Br2, leading to a reduction in the band gap width. The band gap for undoped Bi4O5Br2 was 2.151 eV, whereas the Ni-doped system exhibited a smaller band gap, directly indicating its enhanced visible light absorption capacity and facilitating the effective separation of photo-generated electron–hole pairs. Through analysis of 2D charge density maps, we observed changes in chemical bonding induced by Ni doping. The shortening of Ni-O bonds suggested increased bond strength, consistent with the observed reduction in cell volume. These findings provide a theoretical foundation for understanding the mechanisms behind the enhanced photocatalytic hydrogen production performance in Ni-doped Bi4O5Br2, offering valuable insights for the design and optimization of highly efficient photocatalytic materials.

Experimental method for warm dense matter ionization distribution based on X-ray fluorescence pectroscopy

Warm dense matter (WDM), a state of matter that lies at the frontier between condensed matter and plasma, is one of the main research objects of high energy density physics (HEDP). Comparing with the isolated atom, the electron structure of WDM will change because of the influence of density and temperature effect. Both the accurate theoretical representation and the accurate experimental study of WDM electron structure are challenging, as it is strongly coupled and partially degenerated. In this work, an experimental method of studying the ionization distribution of WDM based on X-ray fluorescence spectroscopy is developed. In the experiment, in a specially designed hohlraum, warm and dense titanium with several tens of electron volts and nearly solid density is produced by simultaneous driving of high-energy X-ray heating and shock compression. Then, using the characteristic line spectrum emitted by the laser irradiation on pump material (Vanadium) as a pump source, the titanium emits fluorescence. The X-ray fluorescence spectra of titanium with different states (cold sample, 1.8–4.5 g/cm&lt;sup&gt;3&lt;/sup&gt; and 1–25 eV) are diagnosed by changing the experimental strategy. The experimental results indicate that the line profiles of K&lt;sub&gt;&lt;i&gt;α&lt;/i&gt;&lt;/sub&gt; and K&lt;sub&gt;&lt;i&gt;β&lt;/i&gt;&lt;/sub&gt; fluorescence spectrum of the heated sample change obviously compared with those of the cold sample. According to the theoretical calculation of the two-step Hartree-Fock-Slater (TSHFS) method, the main reason for the change of the line profile is the change of ionization distribution caused by temperature rising. The future work will focus on optimizing the experimental method of X-ray fluorescence spectrum, such as improving the spectrum resolution, characterizing the temperature and density experimentally, obtaining a set of ionization distribution data, and then studying the influence of dense environment on electronic structure.

First-principles study of magnetic properties and electronic structure of 3d transition-metal atom-adsorbed SnSSe monolayers.

We investigated the electronic structure and magnetic characteristics of 3d transition metal elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) adsorbed onto monolayer SnSSe by employing first-principles calculations. After the calculation, we found that Sc, Ti, V, Cu, and Zn atoms adsorbed onto monolayer SnSSe do not have magnetic moments, while the rest of the atoms adsorbed onto SnSSe are able to produce magnetic moments, and their magnetic moments in the adsorption systems are in the range of 1.0-3.0 μB, in which the magnetic distance of Mn is the largest. The results of MAE calculations indicate that there is a big difference in the MAE of the systems with TM atoms adsorbed to the S-side and the Se-side; for V adsorbed to the S-side on the Sn atoms, the MAE is the largest, which reaches 8.277 meV f.u.-1, showing an in-plane magnetic anisotropy, and for Co adsorbed to the Se-side on the Sn atoms, the MAE is the smallest, which is -0.673 meV f.u.-1, showing a perpendicular magnetic anisotropy. Calculations of binding energies show that all atoms are able to adsorb stably. Our results indicate the potential application of TM-adsorbed SnSSe monolayers in spintronics and magnetic memory devices.

Electronic Structure Studies with Spin-Orbit Coupling Effect of the Molecule TlI

To study the low–lying electronic states of the TlI molecule, the electronic structure of this molecule has been investigated via an ab initio Complete Active Space Self Consistent Field and the Multireference Configuration Interaction with Davidson correction calculation (CASSCF/MRCI+Q). In the representations of 2s+1Λ(+/−) and (±), the adiabatic potential energy curves (PECs) along with static and transition dipole moment (DM) curves for 19 low-lying electronic states for TlI molecule have been investigated. For the low-lying electronic states of this molecule, the spectroscopic constants Re, Te, ωe, and Be, are provided. Based on the data obtained, this molecule is not a candidate for a Doppler laser cooling study.

The Electronic Structure, Stability, Thermodynamics And Vibrational Study of Cis Alkenyl Substituted Chalcones by Density Functional Theory Calculations

The Electronic Structure, Stability, Thermodynamics And Vibrational Study of Cis Alkenyl Substituted Chalcones by Density Functional Theory Calculations

Study of Geometrical, Electronic Structure, Spectral, and NLO Properties of Phenyl‐Based Azo Dyes of Dye Sensitizer for Solar Cells: A Theoretical Study

AbstractThe molecular geometry, electronic structure, and absorption spectra of some important phenyl derivatives are investigated by using DFT and TD‐DFT with B3LYP and CAM‐B3LYP functional. The highest HOMO–LUMO energy gap, Non‐linear optical properties of dipole moment, polarizability, and hyperpolarizability are calculated. In both methods hyperpolarizability PDP values (16.77 × 10−30 and 16.59 × 10−30 esu) are higher than PDNA, PDN, and MPAN dye. The Molecular electrostatic potential shows that PDNA dye has more electronegative potential. Comparing all the dyes, PDP dye shows a higher light harvesting efficiency in the UV–vis region. The vibrational frequencies are assigned based on the potential energy distribution (PED) using the VEDA‐4 program.

Variability of the Raman Optical Activity Spectroscopy

Spectroscopy of Raman optical activity (ROA) is rather rare because of its experimental demands and difficult interpretation of the spectra. Yet it is further developing and in the last decade we witnessed significant improvement of the experimental and theoretical methods. This brought about new knowledge regarding structure and behavior of molecules, and their interactions with light. We give a brief summary of the experience we and others obtained with this method. It appears that ROA spectroscopy gives unique information about molecules, suitable for determination of the absolute configurations, but also for studies of conformations and electronic structure.

Theoretical study of electronic structure and ionization spectrum of γ-pyrone

The electronic structure and ionization spectrum of γ-pyrone (4 H -pyran-4-one) were studied using the third-order algebraic-diagrammatic construction method for a one-particle Green’s function [IP-ADC(3)] and a number of other high-level quantum chemical methods. The results of the calculations are used to interpret the recently obtained photoelectron spectra. A number of new assignments are proposed concerning the nature of the photoelectron maxima of γ-pyrone above 12 eV, where, according to our calculations, there is a significant violation of the single-electron ionization picture due to electron correlation effects. The results obtained significantly change the interpretation of the spectrum available in the literature.

Structure-search-revealed edge reconstruction in two-dimensional materials: The case of phosphorene nanoribbons

The edge structures of two-dimensional materials are important for the property control of corresponding nanoribbons, but possible edge reconstructions are difficult to resolve. Taking phosphorene nanoribbons as an example, we have employed the structure-searching program IM2ODE to discover new structures for both zigzag and armchair edges of bare phosphorene nanoribbons. The edge atoms of these low-energy nanoribbons are generally 3-fold coordinated, and the edge energies are significantly lower than those directly cut from the monolayer. Moreover, we can build low-energy sinuous edges along the diagonal direction based on the bonding features of phosphorus atoms. Further electronic structure studies also reveal that zigzag phosphorene nanoribbons undergo cell doubling and metal-insulator transition similar to Peierls distortion, indicating that the edges experience self-passivation and become stabilized. As similar edge reconstructions can exist in many other two-dimensional materials and it may be difficult to construct the edges by hand, our structure-searching approach provides reliable insights and certain rules can be discovered to elucidate various structure reconstructions.

CO2 and CO Capture on the ZnO Surface: A GCMC and Electronic Structure Study

CO₂ and CO Capture on the ZnO Surface: A GCMC and Electronic Structure Study

Density-functional study of electronic structure of quantum dots in high magnetic fields

Density-functional theory is used to study the electronic structure of quantum dots in magnetic field. New series of magic numbers are found for the total angular momentum of electrons. The empirical formula for the plateau width is obtained. The effect of a charged impurity on the electronic structure of a quantum dot has been studied.