Journal of Research on Many-body Systems
https://jrmbs.scu.ac.ir/
Journal of Research on Many-body Systemsendaily1Mon, 23 Oct 2023 00:00:00 +0330Mon, 23 Oct 2023 00:00:00 +0330Photocatalytic activity of graphite-Fe-Ti alloy for the removal of dye pollutant: Synthesis, characterization and optimization studies
https://jrmbs.scu.ac.ir/article_18510.html
This research investigates the photocatalytic activity of mechanically alloyed graphite-iron-titanium powder for the removal of Eriochrome Black-T dye pollution. The structural and optical properties of the alloys are evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy diffraction spectroscopy (EDX), and ultraviolet-visible spectroscopy (UV-vis). X-ray diffraction measurements show that after 35 hours of milling time, the intensity of the element&rsquo;s peaks decreases, along with the increase of peaks width. The average iron crystallite size is estimated to be approximately 50.8 nanometers. The morphology of the alloyed powders shows that the particles are flattened and plate-like in shape, which is suitable for absorption and photocatalytic activities. Fifteen photocatalytic experiments are designed to remove dye pollution; the optimal dye removal&rsquo;s parameters for pH, lamp power, and alloy dosage (g/L) are obtained using the combination of artificial neural network, and genetic algorithm (ANN-GA). With optimal conditions, the maximum removal rate is determined to about 86.4%.Spin-dependent electronic transmission coefficient of a nanostructure in the free-electron approximation by transfer matrix method
https://jrmbs.scu.ac.ir/article_18418.html
In this paper, based on the transfer matrix method and within the free electron approximation, we study spin-dependent electronic transport through an array of magnetic quantum barriers. For this purpose, we first write the Schrodinger equation for the electron in the presence of barrier potentials and the magnetic field originating from system magnetic moments. Then, by its discretization, we reach a system of linear equations. In the following, by using the transfer matrix method for this system of equations, we obtain the spin-dependent transmission coefficients of the electron. With the help of present formalism, one can calculate the spin-dependent transmission coefficient of a transmitted electron through a magnetic multi-layer as a function of electron energy, magnitude and orientation of the magnetic moment, and the potential shape. Finally, as an example, the numerical results are presented for two cases, the one including two similar alternative magnetic barriers and the other including two alternative barriers and well. The presented method is useful for the study of the spin-dependent electronic conductance behavior of magnetic layers and superlattices.The analytical determination of binding energy and magnetic moment of light single-lambda hypernuclei
https://jrmbs.scu.ac.ir/article_18419.html
Hypernuclei are known as the bound states of nucleons and one or more strange baryons (hyperons) so the development of their physics helps to understand the structure of nuclei and the properties of strange baryons with more precision. One important goal in the field of hypernucleus physics is the study of the interaction of hyperon-nucleon and hyperon-hyperon. In this regard, the study of hypernuclei structure can play an essential role in understanding these types of interactions. In this work, we study some important static properties of single-lambda hypernuclei (nuclei containing a -baryon) such as their binding energy and magnetic moments. For our calculation, we use the Dirac relativistic wave equation considering a spin-orbit potential and determine the analytical equation of binding energy and magnetic moments. In the following, we will determine these quantities for some light hypernuclei such as &nbsp;and . Our analytical results will be compared with other theoretical results as well as available experimental data.Stability and bifurcation analysis of nonlinear ion-acoustic waves in superthermal electron-positron-ion plasmas
https://jrmbs.scu.ac.ir/article_18420.html
In this study, the stability and bifurcation analysis of nonlinear ion-acoustic waves is investigated in a non-Maxwellian plasma consisting of cold ions and Kappa-distributed electrons and positrons.&nbsp; First, a characteristic equation for the evolution of ion-acoustic waves is obtained and then the stability of traveling wave solution on fixed points-energetic positron density plane is discussed numerically. It is found that the motion dynamics of homoclinic orbits and nonlinear periodic orbits undergo a transcritical bifurcation at the critical positron density , where two fixed points coalesce, and then switch their stabilities. The variations of the initial &nbsp;and critical &nbsp;positron concentrations versus a wide range of values of the spectral index of positrons &nbsp;and electron-to-positron temperature ratio &nbsp;are also studied. Furthermore, according to the phase portraits analysis, the coexistence of homoclinic orbits, nonlinear periodic, and super nonlinear periodic orbits is also investigated for different conditions. It is shown that the positron density and the temperature ratio of electron to positron play a crucial role in the propagation of nonlinear waves.Traversable wormholes in Einsteinian cubic gravity with variable red-shift functions
https://jrmbs.scu.ac.ir/article_18500.html
In this work, we study wormhole solutions described by a radial dependent red-shift function in Einstein-cubic gravity. We derive wormhole solutions by assuming a particular equation of state and check the standard energy conditions. These solutions by imposing suitable values the parameters of the theory satisfy the weak energy condition in the vicinity of the throat. We calculate the null and time-like geodesic equations in the space-time of the wormhole solutions. In addition, by using these solutions and the effective potential formalism, some geodesics are classified. We discuss the geodesics of the test particles and classify them according to the particle&rsquo;s energy and angular momentum. Finally, using gravitational lensing effects, observational features of the wormhole structure are discussed.Nonclassical properties of binomial state in inertial and accelerated motion
https://jrmbs.scu.ac.ir/article_18417.html
In this article, we considered the effect of uniform acceleration on the quantum binomial state, which consists of a superposition of single-mode Fock states with binomial coefficients. In particular, we studied the nonclassical features of the quantum binomial state under Unruh effect. We obtained analytically various witnesses of nonclassicality such as squeezing, Mandel parameter, and Vogel&rsquo;s criterion. We found that squeezing could be increased or decreased by the Unruh effect for different observers.&nbsp; In addition, with the increase of the number of single-mode Fock states in the quantum binomial state, the squeezing increases. Moreover, we found the Mandel parameter and Vogel&rsquo;s criterion which is a sufficient condition for the nonclassicality of the state and compared the results with the inertial observer.Comparison of electron transport in Graphayne ring and Benzene by using of Tight-Binding model and Density Functional Theory
https://jrmbs.scu.ac.ir/article_18894.html
In this paper, we study the electrical conductance of a molecular bridge consisting of a graphyne ring with the chemical formula C18H6 connected to two cumulene electrodes using the tight-binding model. We then compare its conductance with a similar system in which the graphyne ring has been replaced by a benzene molecule. To do this, we first obtain the structural characteristics of the studied rings using density functional theory, and then, using the method of matching levels, we obtain the tight-binding parameters, i.e., the on-site and the hopping energies for the benzene and the graphyne rings. Using these parameters, we study the electrical conductance for these two molecules, namely, benzene and the graphyne ring. We conclude that when these two molecules are in the same position between two cumulene electrodes, they exhibit the same electrical properties. However, in the graphene ring, a phase transition from metal to semiconductor or vice versa can be created with less energy than in a benzene ring.Temperature effect on the refractive indices and Kerr constant of doped nematic liquid crystals with right-handed dopants
https://jrmbs.scu.ac.ir/article_18895.html
Liquid crystals with high optical and electro-optical responses play an important role in optics and photonics. Therefore, providing a simple method to increase the optical behavior of liquid crystals under the influence of external fields can be considered one of the most challenging research areas. In this experimental work, the effects of temperature and right-handed chiral material with different weight percentages on the refractive indices and optical properties of E7 nematic liquid crystal under the influence of an external electric field were investigated. Despite the reduction of Kerr constant with increasing the weight percentage of chiral dopants and temperature, the highest amount of optical response in the presence of the electric field was obtained for the nematic liquid crystal doped with 3% of right-handed material. In this case, the value of Kerr constant is almost 2 times that of pure liquid crystal. This interesting result can be related to the order parameter changes caused by different molecular interactions. Thus, the results obtained in this research can be used as a simple method to increase the optical response of nematic liquid crystals in the presence of an external electric field.Time Independent of Drift Coefficients for Shape Invariant Potentials
https://jrmbs.scu.ac.ir/article_18896.html
In this research, using the analytical solution of the Fokker-Planck equation, the time-independent drift coefficients for the shape-invariant potentials have been obtained. In this approach, first, the Fokker-Planck equation is converted into a Schr&ouml;dinger-like equation. Then, using the mechanism of supersymmetric quantum mechanics, the Fokker-Planck equation is analytically solved and its explicit solutions are obtained. In this calculation, the diffusion coefficient is considered a constant. This approach is applicable to shape-invariant potentials which are exactly solvable potentials. Exactly solvable potentials refer to potentials for which all eigenvalues and eigenfunctions can be obtained explicitly. These calculations are used to examine the probability density distribution of laser-accelerated carbon beams after entering the fuel region in the fast ignition method.Investigation of Singularity of Central Shape Invariant Potentials
https://jrmbs.scu.ac.ir/article_18897.html
In this research, the singularity of the central shape-invariant potentials, which have a singularity of the inverse-square power &alpha;&frasl;r^۲ , has been investigated. It has been shown that in quantum mechanics, for &alpha;&ge;۳/۴, the eigenvalue problem is well-defined and, as a result, the energy spectrum can be determined. In the transition region, for -۱/۴&le;&alpha;&lt;۳/۴, both regular and irregular wave functions are square integrable and therefore acceptable, but the boundary conditions for determining the eigenvalues and eigenfunctions are not sufficient and there is no a specific predetermined mechanism for choosing a linear combination of wave functions. For &alpha;&lt;-۱/۴, the particle is drawn to the singularity, and therefore, there is no any ground state with finite energy. It has also been shown using supersymmetric quantum mechanics that the inverse-square potential is the result of the singular inverse superpotential &beta;&frasl;r. Supersymmetric quantum mechanics provides a mechanism that, without any additional constraints, the less singular wave function is chosen and the potential is placed in the transition region for -۳/2&lt;&beta;&lt;۱/2.Numerical study of transition rate and B(E2) transition strengths for 17O(p,γ)18F reaction
https://jrmbs.scu.ac.ir/article_18898.html
The study of astrophysical S-factor is one of the methods of analyzing proton radiation capture reactions in the theoretical framework for low temperatures. In this work, we have studied numerically the proton radiative capture reaction by 17O using the Woods-Saxon potential model. At first, the astrophysical S-factor reaction was calculated at low energies, and then the reaction rate of the was obtained from the astrophysical S-factor. Also, in this work, the electrical quadrupole transition strength (B[E2]) for excited states 18F nucleus has been calculated. We were found B[E2] depends on energy and spin of the excited states. The results corresponding to the astrophysical S-factor, reaction rate and transition strength at energy range of 200-500 keV were compared with experimental data and other theoretical models and were in good agreement. Also, the astrophysical S-factor at zero energy was calculated by the extrapolation method for (5/2)+ state and S(0)=4/8 keV b.Structural and electronic properties of InSb1-xBix(x=0, 0.25, 0.5, 0.75, 1)
https://jrmbs.scu.ac.ir/article_18899.html
In this study, the structural properties and electronic band structure of InSb1-xBix (x=0, 0.25, 0.5, 0.75, 1) alloys are investigated using density functional theory utilizing the WIEN2K package. The results related to the structural properties show that the lattice constant, as a function of x, is in excellent agreement with Vegard's linear rule. Calculations involving the investigation of the band structure using the mBJLDA exchange-correlation potential reveal that InSb is a semiconductor with a small gap , exhibiting a normal band order at the &Gamma; point While InBi is a metal that exhibits a band inversion at the &Gamma; point. By adding Bi to InSb and forming InSb0.75Bi0.25 and InSb0.25Bi0.75 alloys, the normal band order and the gap at the &Gamma; point disappear. This leads to a transition from a narrow band gap semiconductor with normal band order (InSb) to a gapless semiconductor (InSb0.75Bi0.25) and a metal (InSb0.25Bi0.75) with an inverted band order. By replacing half of the Sb atoms with Bi atoms in InSb and creating the InSb0.5Bi0.5 alloy, not only an inverted band order is observed at the &Gamma; point, but a band gap is also created and transition from a conventional semiconductor to a topological semiconductor occurs.Simulation and investigation of environmentally friendly CIGS solar cell by Silvaco-ATLAS
https://jrmbs.scu.ac.ir/article_18900.html
In this paper, a CIGS solar cell with a Mo/Cu(In0.7Ga0.3)Se2(CIGS)/CdS/ZnO/Al-doped ZnO (AZO) structure was simulated by Atlas silvaco-TCAD software. The photovoltaic characteristics of solar cell using CdS and ZnSe buffer layers were calculated and compared. Then, the photovoltaic characteristics were examined with different thicknesses of the ZnSe buffer layer. The 25 nm thickness is selected as the optimum thickness. After optimization of the ZnSe layer thickness, the photovoltaic characteristics of solar cell were evaluated by changing the in conduction band offset (CBO). The highest CIGS solar cell conversion efficiency was obtained in the range from -0.5 eV to +0.5 eV for CBO. Finally, graphene was replaced with Al-doped ZnO (AZO) due to its high optical transparency, high carrier mobility, and proper mechanical properties. Graphene was used as monolayer and multilayer as transparent conductive oxide (TCO) layer. Simulations predicted the highest efficiency for solar cell structure based on Mo/CIGS/ZnSe/i-ZnO/monolayer graphene and the photovoltaic parameters were Jsc=38.64 mA/cm2, Voc=0.67 V, FF=79.33% and &eta;=20.71%.