Density Contour Plots Research Articles

Dependence of clay–water contact angle on surface charge and ambient temperature: A study from molecular dynamics perspective

The clay-water contact angle emerges as a pivotal parameter essential for elucidating various engineering challenges. Its variability is closely linked to surface charge and ambient temperature, thereby exerting significant influence on soil’s hydraulic properties. However, current research on the joint effects of ambient temperature and surface charge on clay’s contact angle is incomplete, lacking insights from molecular dynamics perspective. Focusing on Young’s contact angle, this study has established diverse montmorillonite-water systems under varying surface charge conditions (cation exchange capacity = 0, 27.60, 54.84, 108.38, and 134.73 meq/100 g) and ambient temperatures (277, 293, 313, 353, 393, and 433 K) through the molecular dynamics (MD) method. The liquid phase boundary is determined by extracting density contour plots and a unified conical curve is introduced to quantitatively analyze the contact angle calculated by MD simulations. This approach led to the development of a nonlinear equation for estimating contact angle variations under different surface charges and ambient temperatures. Finally, the proposed equation is validated against literature data, demonstrating a strong correlation with experimental findings. It exhibits remarkable accuracy in predicting the variations of contact angles induced by ambient temperature under various surface charge conditions. These findings offer valuable insights and practical equation for designing clay impermeable layers in engineering applications.

Optical assessment of vertical TFET based on heterojunction of GaSb-Si

This paper investigates the electrical and opto-sensing analysis of hetero stack vertical TFETs based on III/V group Gallium antimonide (GaSb)-Si at various wavelengths within the visible spectrum. Initially, the drain current, energy band diagram, and electron density contour plot are extracted in order to study the DC and electrical behavior of the device. Following that, their performance is evaluated by altering the source side thickness and observe the tunneling rate of device. Furthermore, the photo application of the device is noticed by computing the critical optical parameter such as sensitivity (Sn), noise factor, and efficient characteristics. Finally, a comparative table is included to set the benchmark and highlight the importance of hetero stack TFET. The device's maximum reported sensitivity is approximately 25.2 and responsivity (R) is 0.8 A/Watt at 320 nm wavelength. Additionally, we examined the effect of trap charges under light state at the gate-channel, isolator-channel, and source-channel interface respectively.

Theoretical studies on phase stability, electronic, optical, mechanical and thermal properties of chalcopyrite semiconductors HgXN2 (X=Si, Ge and sn): A comprehensive DFT analysis

In this study, the ground state physical properties of Hg-based chalcopyrite semiconductors, HgXN2 (X = Si, Ge and Sn), are investigated using the density functional theory (DFT), which is based on full potential linearized augmented plane wave (FP-LAPW) method. The structural, electronic, optical, mechanical and thermal properties of the body-centered tetragonal (BTC) phase, HgXN2 (X = Si, Ge and Sn), have been calculated using the modified Becke-Johnson exchange-correlation potential (TB-mBJ). The obtained lattice parameters and volume are in good agreement with the values reported earlier, indicating that the results are reliable and reproducible. The phase stability of the titled compounds is elaborately studied and it is confirmed that all are thermodynamically, dynamically and mechanically stable. The electronic band structure demonstrated a direct band gap of 1.70 eV, 0.99 eV, and 0.94 eV for the HgXN2 (X = Si, Ge and Sn) compounds, respectively. Both HgGeN2 and HgSnN2 compounds have a notably lighter carrier effective mass, resulting in higher carrier mobility and conductivity than HgSiN2. The order of the mechanical hardness is as follows: HgSiN2> HgGeN2> HgSnN2. The studied materials are also anisotropic in mechanically and optically. All the title compounds exhibit ductile behavior. The charge density contour plots indicates the dominant covalent nature of the bonds in HgXN2 (X = Si, Ge and Sn). All these compounds have a high absorption coefficient and low optical reflectivity in the visible light range. Due to the favorable band gap and high absorption coefficient, these compounds could be suitable for optoelectronic or photovoltaic device applications. Moreover, the thermal expansion coefficient, thermal conductivity, melting point and fracture toughness behavior have been calculated, which also showed promise for thermal barrier coating (TBC) applications.

Ab-initio investigation of structural, opto-electronic, and thermodynamic properties of ZnAl2Se4 for photovoltaic applications

In this manuscript, the structural, opto-electronic, and thermodynamic properties of ZnAl2Se4 chalcogenide compounds were studied in detail using the full potential linearized augmented plane wave method. The exchange and correlation potentials used in density functional theory were calculated using local density approximation, the generalized gradient approximation (GGA) method, and the modified Becke–Johnson (mBJ) potential using Wien2k code. The obtained results were compared with each other as well as with available experimental data. At ambient conditions, ZnAl2Se4 is a direct wide bandgap (Г–Г) semiconductor with a bandgap of 2.1 and 3.3 eV with GGA and mBJ potentials, respectively. Density of states (DOS; total DOS and Partial Density Of States (PDOS)) and electron density contour plots were in similar accordance with bandgap, showing semiconductive behavior and covalent bonding nature. The optical properties like the real and imaginary parts of the dielectric constant, the energy loss function L( ω), and the conductivity σ( ω) were calculated. Optical aspects show interaction among phonon and electron in terms of long-range and short-range forces. The studied compound is very useful for various linear–nonlinear optical devices, so this compound is very valuable for several linear–nonlinear optical devices. So this manuscript represents a comprehensive approach for calculating the complete set of useful properties of the ZnAl2Se4 compound, which can provide support for understanding various device phenomena such as electrochemical sensing, photovoltaics, and nonvolatile electronic memories.

Numerical Flowfield Visualization Over Heat Shield Of Satellite Launch Vehicle at Mach 0.8 - 3.0

The paper presents a numerical flowfield visualization over a typical payload shroud of a satellite launch vehicle at Mach number range of 0.80 -3.0 and Reynolds number range of 33 x 106 - 46 x 106 /m. The numerical simulation over the bulbous heat shield is carried out by solving time-dependent compressible axisymmetric turbulent Reynolds-averaged NavierStokes equations. The closure of these equations is obtained employing the Baldwin-Lomax turbulence model. A three-stage Runge-Kutta time-stepping scheme has been used in conjunction with finite-volume discretization of the computational domain. The flowfield features over the bulbous heat shield have been analyzed from the velocity vector and the density contour plots. Flow separation on the payload shroud due to the normal shock wave is observed at Mach number 0.80 and 0.90. The normal shock movement on the heat shield is simulated for various transonic Mach number. A recirculation zone of flowfield is formed in the boat-tail region of the heat shield. The vorticity formation ahead of the heat shield moves close to the heat shield with the increasing transonic Mach number, which is observed in the density contours plots of the flowfield. Shock stand-off distance at the supersonic speed is calculated and compared with asymptotic formula of Frank and Zierep. They are found in good agreement.

Towards numerical simulation of fatigue damage detection in CFRP laminates by modelling of stochastic vibration response

Due to the widespread use of composites in aerospace applications, there is an increasing need for developing Structural Health Monitoring (SHM) systems for composite structures. In this process, simulation models can play a crucial role by contributing to the optimization of the experimental techniques and to understanding of the physical mechanisms. The objective of this work is to numerically simulate fatigue damage detection in laminated composites subjected to random vibration through a white gaussian noise. To this end, the ANSYS FE code has been used. The developed FE model represents an experimental set-up consisting of the composite specimen, the speakers producing the white noise and the measuring equipment. 24 specimens were modelled in total, a healthy one and 23 damaged ones. The white noise was modelled by introducing a normalized sequence of numbers adapted to the free vibration eigenfrequency range. Fatigue damage in the form of matrix cracking and delamination was modelled based on C-Scan images of fatigued specimens by degrading the appropriate elastic properties of the layers in specific groups of elements. Damage of different geometry, size, and type was modelled. The numerical results are in the form Power Spectral Density (PSD) diagrams, natural frequencies, eigenfrequencies and contour plots. The comparison between the numerical and experimental eigenfrequency values show a maximum deviation of 1.7%. The numerical results show a change in the vibration response even in the presence of a small damage, which is an indication of the sensitivity of the method. A significant decrease in natural frequencies of the specimen with the damage accumulation is observed. The present model comprises the first effort towards a fully validated digital twin which will be used for the virtual testing and the optimization of the vibration test.

Importance of surface morphology on secondary electron emission: a case study of Cu covered with carbon, carbon pairs, or graphitic-like layers

Understanding the relationship between surface adsorbates and secondary electronic emission is critical for a variety of technologies, since the secondary electrons can have deleterious effects on the operation of devices. The mitigation of such phenomena is desirable. Here, using the collective efforts of first-principles, molecular dynamics, and Monte Carlo simulations, we studied the effects of a variety of carbon adsorbates on the secondary electron emission of Cu (110). It was demonstrated that the adsorption of atomic C and C_2 pair layers can both reduce and increase the number of secondary electrons depending on the adsorbate coverage. It was shown that under electron irradiation, the C–Cu bonds can be dissociated and reformed into C_2 pairs and graphitic-like layers, in agreement with experimental observation. It was verified that the lowest secondary electron emission was due to the formation of the graphitic-like layer. To understand the physical reason for changes in number of secondary electrons for different systems from an electronic structure perspective, two-dimensional potential energy surfaces and charge density contour plots were calculated and analyzed. It was shown that the changes are strongly influenced by the Cu surface morphology and depends highly on the nature of the interactions between the surface Cu and C atoms.

Physical properties of elastically and thermodynamically stable magnetic AcXO3 (X = Cr, Fe) perovskite oxides: a DFT investigation

Spin-polarized calculations of mechanical, electronic structure, phonon, optical and magnetic properties of AcXO3 (X = Cr, Fe) perovskite oxides (POs) has been computed using the full-potential linearized augmented plane wave method. The modified Becke Johnson (mBJ) approximation has been utilized for exchange-correlation potential and implemented in the WIEN2k code. The negative values of formation energy and the positive fRequencies of the phonon modes show the stability of studied perovskite oxides. The mechanical stability is confirmed through the elastic parameters such as shear modulus (G), Bulk modulus (B), Poisson ratio (ν) and Cauchy pressure. The semiconductor nature with an indirect bandgap is observed for both compounds in both spin channels. The computed electron density contour plot describes the bonding nature of both compounds. The magnetic moments are calculated, which show the major involvement of Fe and Cr atoms in the overall magnetism of studied compounds. The optical response is also evaluated, showing the maximum absorption in the ultraviolet region. The overall analysis of the calculated properties shows that the studied oxide perovskites are suitable for spintronic and optoelectronic applications.

Cooperativity and intermolecular hydrogen bonding in donor‐acceptor complexes of phenol and polyhydroxybenzenes

AbstractCooperativity between intermolecular and intramolecular hydrogen bonds is an important factor determining the strength of donor‐acceptor complexes. Its impact in poly‐1,2‐diols, notably polyhydroxybenzenes, is subject to debate. Density functional theory calculations have been performed on complexes of phenol, catechol, pyrogallol and 1,2,3,4‐tetrahydroxybenzene with pyridine, trimethylamine and trimethylphosphine oxide. Binding energies, proton NMR shifts, Quantum Theory of Atoms in Molecules analysis and Interacting Quantum Atoms (IQA) interaction energies reveal a positive cooperative effect of a topological intramolecular hydrogen bond (IMHB) in catechol relative to phenol, with insignificant or small negative effects of further HO groups. Except for catechol complexes, there are no topological IMHBs in any donors or their complexes, although all show Non‐Covalent Interaction isosurfaces. The absence of a topological IMBH in catechol itself is explained by electron density contour plots. Complexes of Me3N and Me3PO with catechol, pyrogallol and 1,2,3,4‐tetrahydroxybenzene display additional intermolecular hydrogen bonds, C‐H…H‐C and C‐H…O=P, respectively, with the hydrogen atom ortho to the bound HO group. The predominantly covalent or electrostatic character of the various hydrogen bond types is discussed in terms of the IQA energy partition scheme, which is also useful for characterising IMHBs in the absence of a bond critical point. These results further our understanding of the nature and the limits of cooperative hydrogen bonding in donor‐acceptor complexes.

On the origins of spontaneous spherical symmetry-breaking in open-shell atoms through polymer self-consistent field theory.

An alternative approach to density functional theory based on self-consistent field theory for ring polymers is applied to neutral atoms hydrogen to neon in their ground-states. The spontaneous emergence of an atomic shell structure and spherical symmetry-breaking of the total electron density are predicted by the model using the ideas of polymer excluded-volume between pairs of electrons to enforce the Pauli-exclusion principle and an exact electron self-interaction correction. The Pauli potential is approximated by neglecting inter-atomic correlations along with other types of correlations, and comparisons to Hartree-Fock theory are made, which also ignores correlations. The model shows excellent agreement with Hartree-Fock theory to within the standards of orbital-free density functional theory for the atomic binding energies and density profiles of the first six elements, providing exact matches for the elements hydrogen and helium. The predicted shell structure starts to deviate significantly past the element neon, and spherical symmetry-breaking is first predicted to occur at carbon instead of boron. The self-consistent field theory energy functional that describes the model is decomposed into thermodynamic components to trace the origin of spherical symmetry-breaking. It is found to arise from the electron density approaching closer to the nucleus in non-spherical distributions, which lowers the energy despite resulting in frustration between the quantum kinetic energy, electron-electron interaction, and the Pauli exclusion interaction. The symmetry-breaking effect is found to have a minimal impact on the binding energies, which suggests that the spherical-averaging approximation used in previous work is physically reasonable when investigating atomic systems. The pair density contour plots display behavior similar to polymer macro-phase separation, where individual electron pairs occupy single lobe structures that together form a dumbbell shape analogous to the 2p orbital shape. It is further shown that the predicted densities satisfy known constraints and produce the same total electronic density profile that is predicted by other formulations of quantum mechanics.

A quantitative characterization of the spatial distribution of brain metastases from breast cancer and respective molecular subtypes.

Brain metastases (BM) remain a significant cause of morbidity and mortality in breast cancer (BC) patients. Specific factors promoting the process of BM and predilection for selected neuro-anatomical regions remain unknown, yet may have major implications for prevention or treatment. Anatomical spatial distributions of BM from BC suggest a predominance of metastases in the hindbrain and cerebellum. Systematic approaches to quantifying BM location or location-based analyses based on molecular subtypes, however, remain largely unavailable. We analyzed stereotactic Cartesian coordinates derived from 134 patients undergoing gamma- knife radiosurgery (GKRS) for treatment of 407 breast cancer BMs to quantitatively study BM spatial distribution along principal component axes and by intrinsic molecular subtype (ER, PR, Herceptin). We used kernel density estimators (KDE) to highlight clustering and distribution regions in the brain, and we used the metric of mutual information (MI) to tease out subtle differences in the BM distributions associated with different molecular subtypes of BC. BM location maps according to vascular and anatomical distributions using Cartesian coordinates to aid in systematic classification of tumor locations were additionally developed. We corroborated that BC BMs show a consistent propensity to arise posteriorly and caudally, and that Her2+ tumors are relatively more likely to arise medially rather than laterally. To compare the distributions among varying BC molecular subtypes, the mutual information metric reveal that the ER-PR-Her2+ and ER-PR-Her2- subtypes show the smallest amount of mutual information and are most molecularly distinct. The kernel density contour plots show a propensity for triple negative BC to arise in more superiorly or cranially situated BMs. We present a novel and shareable workflow for characterizing and comparing spatial distributions of BM which may aid in identifying therapeutic or diagnostic targets and interactions with the tumor microenvironment. Further characterization of these patterns with larger multi-institutional data-sets may have major impacts on treatment or management of cancer patients.

A DFT study of ZnO, Al2O3 and SiO2; combining X-ray spectroscopy, chemical bonding and Wannier functions

The electronic properties of a group of oxides with important technological applications were studied performing ab initio calculations. Al2O3 is an important ceramic and catalyst, suitable insulator for electronic applications and nano scale access memory. SiO2 is important from both geological and materials science point of view. Pure and doped ZnO structures have direct industrial applications in lasers, sensors, and infra-red and luminescence sensitive devices.A Full Potential Linearized Augmented Plane Waves (FP-LAPW) method within the Density Functional Theory (DFT) formalism was applied to study electronic properties of these oxides and different post-processing tasks as contour plots of electronic charge density, projected densities of states, band structure, Bader's method and Maximally Localized Wannier Functions were used to analyse the electronic charge transfer and bonding properties of the systems. The positions of these Wannier functions, shown in histograms and 3D plots, opened the possibility to calculate the bonding ionicity trend of materials. We report X-ray spectra obtained from self consistent ab initio calculations. K and L2,3 edges were calculated including the fractional electronic core-hole and double core-hole providing similar features as in the reported experimental X-ray absorption near edge structure (XANES).

Analysis of a Hypothetical Complete Loss-of-Coolant Accident in a Typical Research Reactor

In the present study, an analysis of a hypothetical complete loss-of-coolant accident in a typical open-pool research reactor is conducted. The reactor core is assumed to be completely uncovered and exposed to the ambient air. The possibility of passively cooling the decay heat of the exposed reactor core by natural convection to air and thermal radiation until core reflooding is investigated. A three-dimensional computational fluid dynamics analysis is conducted for the uncovered core while cooled by air natural convection and thermal radiation. The reactor core is simulated as a porous zone with decay heat generation specified as a cosine-shape distribution. The reactor core decay heat acts as a driving force for the coolant flow from the cold leg to the hot leg. The thermal equilibrium porous media model is used to represent the energy equation inside the core region. This study is conducted for core uncover time (the time interval between reactor shutdown and the moment when the reactor core is drained of water) of 10E3, 10E4, 10E5, 10E6, 10E7, and 10E8 s. Contour plots of temperature, velocity, density, and pressure at different values of core uncover time are illustrated. It’s found that for core uncover times of 10E3, and 10E4 s, the maximum core temperature exceeds the cladding melting point. The core maximum temperature is well below the melting point for uncover times of 10E5, 10E6, 10E7, and 10E8 s.

Effects of adiabatic flame temperature on flames’ characteristics in a gas-turbine combustor

In this study a comparison between the premixed methane oxygen-enriched-air (CH4/O2/N2) and oxy-methane (CH4/O2/CO2) in a gas-turbine model combustor that imitates pre-mixers in operational air-fuel dry low emissions gas turbines is presented. The comparison and analyses that follow in this study are based on the results of experiments conducted. The combustion stability maps were obtained through the estimation of acoustic limits and measurement of blowout limits within the space of equivalence ratio (φ) – oxygen fraction (OF). The stability maps obtained were superimposed on the contour plots of constant adiabatic temperature (Tad), Reynolds number (Re), and power density (PD) of the combustor. Effects of Tad on flame macrostructure, flame stability, flame speed, and blowout mechanism were investigated. The temperature distributions were also measured. The study results indicated that blowout of CO2 as well as N2 flames occur at constant Tad. These results are more pronounced in the case of the multi-hole burner because, such burner is not characterized with sporadic nature of flame lifting and reattachment that dominate the occurrence of a blowout in swirl burner; for a given OF, φ at which CO2 flames blowout is higher than that of N2 flames due to the poorer resistance of oxy-flames to blowout as compared to air flames; the stable combustion zone of CO2 flames is larger than that of N2 flames.

An Optimum Structure of Scalable Capacitors in 3D Crosspoint Memory Technology

Memory chips need large capacitors in their periphery to drive boosted word-lines and bit-lines for read and write operations. In a previous work, scalable capacitors were proposed for 3D crosspoint memory to keep the area for the capacitors constant over technology generations. This paper proposes the capacitance models of three types of wiring capacitors: (1) vertical capacitor, (2) vertical and horizontal capacitor with next-neighbor wires connected with the other terminal, and (3) vertical and horizontal capacitor with next-neighbor pairs connected with the other terminal. These models are based on Wong’s crossover capacitor model to determine the capacitor structure with the highest capacitance density in 3D crosspoint memory technology. One can determine the best structure through optimizing the process parameters such as the height H of the insulation material between the metal wires and the thickness T of the metal wires and the design rules such as the width W and space S of metal wires. The model accuracy was in good agreement with the measurement of twelve types of capacitor structures fabricated in a 180 nm 6 metal standard CMOS process with the maximum error of 20%. Contour plots of the capacitance density across H vs. S where it is assumed that W = T = S are shown. As a result, the boundary condition regarding H and S is determined per 3D crosspoint memory technology with three, four, or five levels of wires.

Theoretical Investigation of CsBX3 (B = Pb, Sn; X = I, Br, Cl) Using Tran–Blaha Modified Becke–Johnson Approximation for Flexible Photoresponsive Memristors

AbstractThe structural, elastic, charge conduction and photoresponsive properties of halide perovskites, i.e., CsBX3 (B = Pb, Sn; X = I, Br, Cl) are investigated using the full potential‐linearized augmented plane wave (FP‐LAPW) method in the frame work of density functional theory (DFT). Perdew Burke Ernzerhof (PBE) functional belonging to the generalized‐gradient approximation (GGA) is implemented. For the better estimation of electronic parameters, the Tran–Blaha modified Becke–Johnson (TB‐mBJ) potential is employed. The elastic parameters such as bulk modulus, shear modulus, Young's modulus, the Pugh's ratio, anisotropy factor, Poisson's coefficient, and melting temperature (Tm) are estimated within Voigt‐Ruess‐Hill approximations. The energy band structure results, total density of states (TDOS), partial density of states (PDOS) outcomes, and isosurface charge density contour plots disclose that Sn2+and I1− are more appropriate divalent cation and anion respectively, among all studied composites especially for the application of photoresponsive resistive random access memory (RRAM) devices. Moreover, partial density of states (PDOS) outcomes depict that conduction band formation is consequence of hybridization of electrons from p‐orbitals of divalent cations, i.e., Pb, Sn and I/Br/Cl halogen anions. Besides, regarding charge conduction Sn‐based composites offer minimal energy bandgap as compared to Pb‐based composites. The energy bandgap order for Sn‐based compounds is found as CsSnI3> CsSnBr3> CsSnCl3. The optical analysis renders that CsSnI3 have the capability to absorb a wide range of ultraviolet (UV), visible and infrared (IR) electromagnetic incident radiations thus, make it much suitable material for optoelectronic memristors and associated applications.

Application of Rainbow Schlieren Deflectometry for Jets from Round Laval Nozzles Followed by Cylindrical Ducts

The jet from a round Laval nozzle followed by a cylindrical duct with an inner diameter of 10 mm and a length of 50 mm is investigated experimentally. The Laval nozzle has a design Mach number of 1.5. Quantitative flow visualization of the jet issued from the duct exit is performed over a range of nozzle pressure ratios from 2.0 to 4.5 using the rainbow schlieren deflectometry combined with the computed tomography to investigate the jet three-dimensional structure. The flow features of the near-field shock systems in the jets are displayed with the density contour plot at the cross-section including the jet centerline. Effects of the nozzle pressure ratio on the density profile along the jet centerline are clarified quantitatively. In addition, a comparison between the present experiment and the previous one with a conventional Laval nozzle for jet centerline density profiles is carried out to examine the effect of the cylindrical duct. Furthermore, the three-dimensional structures of overexpanded and underexpanded jets are demonstrated with the isopycnic surfaces to visualize the internal flow features.

Quantitative Flow Visualization of Slightly Underexpanded Microjets by Mach\u2013Zehnder Interferometers

The Mach–Zehnder interferometer with the finite fringe setting is applied for a shock-containing microjet issued from an axisymmetric convergent nozzle with an inner diameter of 1.0 mm at the exit. Experiments are performed at a nozzle pressure ratio of 3.0 to produce a slightly underexpanded sonic jet where the Reynolds number, based upon the diameter and flow properties at the nozzle exit, is 4.45 times 10^4. The reconstruction of the jet density field is performed using the Abel inversion method under the assumption of an axisymmetric flow as well as the Fourier transform method for the phase shift analyses of interferograms. The three-dimensional density field of a shock-containing microjet can be captured with a spatial resolution of 4 upmum, and the near-field shock structure inside the jet plume is shown in the density contour plot at the cross-section including the jet centerline. In addition, the density field of the microjet is illustrated with various techniques, including representation such as the vertical-knife-edge schlieren, the horizontal-knife-edge schlieren, the bright-field schlieren, and the shadowgraphy. In addition to experiments, the Reynolds averaged Navier–Stokes (RANS) simulation with the SST k–omega turbulence model is carried out to model the microjets, and a quantitative comparison with the experiments is performed. The jet centerline density profile obtained by the present experiment is quantitatively compared with those from the previous Mach–Zehnder interferometer, the background oriented schlieren, as well as the RANS simulation.

Distribution in Saturn's Inner Magnetosphere From 2.4 to 10 RS: A Diffusive Equilibrium Model

AbstractElectron density measurements have been obtained by the Cassini Radio and Plasma Wave Science (RPWS) instrument covering the period from 30 June 2004 to 19 April 2017, spanning latitudes up to ~30° and L values from 2.4 to 10. Near the F ring, electron densities are derived from RPWS measurements of electron plasma oscillations at high latitudes and from the Langmuir Probe (RPWS/LP) sweep data at low latitudes. The electron density measurements from the ring‐grazing orbits, beginning in December 2016, have made it possible to extend the work of a previous diffusive equilibrium model to include the distribution of the ring plasma. Beyond the ring‐grazing orbits, the densities are derived from RPWS measurements of the upper hybrid resonance frequency. These density measurements are used to anchor the fit of an expanded diffusive equilibrium density model for a two‐species plasma consisting of water group and hydrogen ions in Saturn's inner magnetosphere. Density contour plots for the two ion species and the electrons are presented. The distribution of the derived plasma densities is consistent with two primary sources, the Enceladus plume and the extended ring atmosphere. There is also an indication of a weaker plasma source at Dione. In the region just outside the A ring and in the region including the Enceladus orbit, the diffusive equilibrium model also shows the expansion of lighter ions and electrons to higher latitudes along the magnetic field lines with evidence of a weaker plasma expansion between the orbits of Tethys and Dione.

Optical properties of lead-free perovskite Cs2InAg(BrxCl1−x)6 for solar cell applications: A DFT study

Organic-inorganic metal halide perovskites have emerged as promising materials for low-cost, high-efficiency solar cells. Chemical compositional tuning along with different device structures for fabrication and interfacial engineering made the record PCE of perovskite solar-cells reaching 25.2%, which is close to that of single crystal silicon solar cells. We investigated the structural, electronic and optical properties of bromine (Br) doped Cs2InAgCl6 in the cubic phase for various doping percentages. The lattice constants were optimized using Birch Murnaghan fit and band gap were found to be increasing as the doping percentage of Br is increased. The theoretical calculations were performed using generalized gradient approximation exchange correlation for all calculations. The optical properties are studied by comparing the absorption coefficients. Contour plots of charge density shows that the nature of chemical bonding is ionic. Band structure plot along high symmetry points revealed a direct band.