Journal of Research on Many-body Systems
https://jrmbs.scu.ac.ir/
Journal of Research on Many-body Systemsendaily1Tue, 21 May 2024 00:00:00 +0330Tue, 21 May 2024 00:00:00 +0330Investigation of the effect of varying magnetic field and Coriolis force on nonlinear ion-acoustic waves in collisional quantum plasma
https://jrmbs.scu.ac.ir/article_19131.html
In this study, a collisional quantum plasma, consisting of positively charged inertial non-degenerate ions and inertialess degenerate electrons, is considered in the presence of the spatially varying magnetic field. The excited nonlinear wave propagation due to changes in the magnetic field and Coriolis force is investigated using the fluid model. The differential equation governing the propagation of ion-acoustic solitons is obtained by the reductive perturbation method. This is a modified Korteweg&ndash;de Vries&ndash;Burgers differential equation where Burger dissipation and collision terms are derived from spatial changes of the magnetic field, the collision of ions with neutral particles, and the effect of Coriolis force. Results of the numerical analysis indicate the combined effect of the magnetic field, the collision of ions with neutral particles, and Coriolis force on the behavior of the ion-acoustic mode causes oscillating and radiating pulses behind the soliton propagation. This equation is converted into the quantum ion-acoustic equation by eliminating spatial changes of the magnetic field and Coriolis force as well as collision of ions with neutral particles.Design and simulation of perovskite-silicon tandem solar cell with high efficiency
https://jrmbs.scu.ac.ir/article_18981.html
The subject of this research is the design and simulation of a perovskite-silicon tandem solar cell. The purpose of this research is to reduce heat loss and increase cell efficiency. In this work, we designed a tandem device consisting of two cells using the SCAPS simulator (Solar Cell Capacitor Simulator); The front cell comprised of CH3NH3PbI3 absorber layer (with a bandgap of 1.55 ev), and a C-Si cell (with 1.12 ev bandgap) was selected as the bottom cell. Each of two cells were simulated and optimized separately, and then, the tandem structure consisting of two cells was simulated and the optimal thickness of the perovskite absorber layer was determined for the current matching conditions in the a two-terminal (2T) monolithic structure. The transmission spectrum of the perovskite cell to radiate to the lower cell was obtained using MATLAB software. Finally, the simulation of this structure led to an efficiency of 33.27%.An ab-initio study of self-interstitial defect evolution in 4H-SiC crystal structure
https://jrmbs.scu.ac.ir/article_18982.html
Macroscopic effects of radiation damage are due to the superposition of initial damages at atomic scale. Using ab-initio molecular dynamics, the effect of point defects on the electronic and structural properties of 4H-SiC was evaluated. According to the results, the position of the defect was the most important factor in the mentioned properties. Based on the ab-initio molecular dynamics, it was depicted that the Frenkel pair recombination occurs only if the hole and defect are close enough (about a lattice constant). It was observed that recombination will happen during 120 to 1600 femtoseconds for carbon and silicon Frenkel pairs, respectively. If recombination does not occur, trap states appear in the energy gap, which can reduce the detector&rsquo;s efficiency.Exploring a suitable partner for Sb2S3 solar cells for use in tandem solar cells
https://jrmbs.scu.ac.ir/article_19015.html
In this research, different tandem solar cells have been designed and simulated, in which the upper sub-cell is Sb2S3. Different structures including Sb2Se3, CISe, CZTSe and GeTe were proposed for the lower sub-cell.It is very important to match the current in the upper and lower sub-cells in consecutive cells. To reach the current matching point, the thickness of the layers of the lower sub-cell was kept constant and the thickness of the absorbing layer of the upper cell was changed so that the current density in both sub-cells was the same. At the current matching point, the performance of the upper cell under the AM1.5G standard spectrum radiation and the performance of the lower sub-cell under the filtered spectrum radiation were evaluated, and then the current-voltage characteristic curve of the tandem cell was obtained from the sum of the characteristic curves of the two sub-cells. The efficiency obtained for Sb2S3/Sb2Se3, Sb2S3/CIS, Sb2S3/CZTSe and Sb2S3/GeTe tandem cells was 22.10%, 30.95%, 24.83% and 36.80%, respectively. The greater the energy gap difference of the sub-cells, the more photons are collected and the greater current density is obtained for the cell. The best performance was obtained when GeTe was used as the bottom sub-cell.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.The study of dynamical phase transitions of a random walker on a one- dimensional lattice with reflecting boundaries
https://jrmbs.scu.ac.ir/article_18980.html
In this paper, we solve a simple model that supports a dynamic phase transition and show conditions for the existence of the transition. we study dynamical phase transitions of a random walker which moves on a one-dimensional lattice with reflecting boundaries. The dynamical activity, which is defined as the number of configuration changes in a dynamical trajectory is considered as the order parameter. We study the dynamical phases in the long-time limit by calculating the scaled cummulant generating function of the activity. It turs out that the system consists of six dynamical phases with both continuous and discontinuous phase transitions. Numerical investigations confirm our analitycal results in the thermodynamic limit.Electron transport in nanostructure lanthanum vanadium oxide quantum dots for solar cells
https://jrmbs.scu.ac.ir/article_19406.html
In this research, we study transport properties of lanthanum vanadium oxide quantum dots, used for solar cell applications. The energy band gap for this material is optimal for converting solar energy into electrical energy according to the Shockley-Queisser limit curve. With the Green's function approach, the electron transport was calculated between the quantum dots of lanthanum vanadium oxide as the central part, which is connected to two metal conductors. This material is considered as a Mott insulating material, therefor we can categorize it among strongly correlated electron systems. To describe this system, Hubbard's model can be used in the second quantization representation, and by using the equation of motion and Dyson's equation, the non-equilibrium Green's function was obtained, and from that, the probability of electron transmission through two and four quantum dots of this material was calculated. The results show that by varying the correlation strength, the optimum Hubbard value is 3.6 eV for the quantum dot system.Study of the electronic and optical properties of graphene-like ZnSe structure considering many body effects
https://jrmbs.scu.ac.ir/article_19407.html
Electronic and optical properties of graphene-like ZnSe were investigated through a comprehensive study using ab initio calculations. By employing the GW method, we accurately determine the electronic band structure and bandgap of graphene-like ZnSe, considering the many-body effects. Additionally, we examine the optical properties of graphene-like ZnSe using the GW+BSE method, calculate the optical absorption spectrum, and determine excitonic properties such as exciton binding energy and optical bandgap. The GW calculations reveal that the ZnSe bandgap is direct with an energy gap of approximately 4.869 eV and exhibits excitons with relatively strong binding energies ranging from 0.2 to 0.8 eV. The majority of bound exciton distributions arise from transitions between Zn(3p)+Zn(3d)+Se(4p) Zn(4s)+Se(4s) at the gamma point in the Brillouin zone. The precise determination of the band structure, bandgap, and excitonic properties enables a better understanding of the material's behavior and aids in the design and optimization of future 2D ZnSe-based devices.Investigation of the type of material and coating of neutron chopper blades on the amount of thermal neutron absorption
https://jrmbs.scu.ac.ir/article_19408.html
Neutron choppers, which work with rotating blades and remove neutrons with unwanted energy, can allow neutrons with a certain energy to pass through. In the design of a neutron velocity selector and the crucial role of these blades in its operation, simulation and experimental studies were performed to investigate the material and type of coating of the blades in relation to thermal neutron absorption. In this study, blades made of cadmium, aluminum, and carbon fiber with different coatings were exposed to thermal neutrons, and the neutron transmission was calculated using the MCNPX code. Based on the simulation results, blades with cadmium coatings and coatings of B4C, LiF, and H3BO3 with specific thicknesses were designed. The thermal neutron absorption of the constructed blades was measured in a thermal neutron flux from an Am-Be source using a BF3 detector. The results show that the cadmium blade without coating (1 mm thick), the aluminum blade (0.5 mm thick), and the carbon fiber blade (0.9 mm thick), both with B4C coatings, have the highest thermal neutron absorption values. The simulation and experimental results show that a B4C coating with a concentration of 35-45 gr&frasl;〖cm〗^2 is suitable for neutron velocity selector blades.Improving hydrogen storage in cobalt/carbon nanotube nanocomposites using cold helium plasma irradiation
https://jrmbs.scu.ac.ir/article_19409.html
In this article, we investigate the radiation of cold plasma composed of helium gas on the amount of hydrogen storage in cobalt/carbon nanotube nanocomposite. For this study, the solution is divided into two parts, one part of which does not receive any radiation from the plasma, and for the other part, before the layers are deposited, a cold plasma consisting of helium gas is applied to the suspension consisting of multi-walled carbon nanotubes. And we irradiate cobalt salt for 30 seconds, then we address the layers by electrochemical method. The results show that plasma treatment even in a short period of time like 30 seconds increases the hydrogen desorption capacity by creating defects and active groups on the surface of nanotubes that are favorable for hydrogen storage.Solitary Wave Solutions of the Multi-Field Sine-Gordon System
https://jrmbs.scu.ac.ir/article_19490.html
In this paper, we introduce solitary solutions of the nonlinear multi-field sine-Gordon system. Despite the use of several independent entangled fields to introduce this system, but the collective behavior of these fields can lead to kink (antikink) solutions with the same macroscopic characteristics. In other words, a kink can be constructed in infinitely different states in terms of internal structure. The important point about this internal structure is that the output of the collisions is effectively dependent on it and we are actually witnessing an uncertainty in the output of the collisions. Radiative solutions are another type of solution of the multi-field sine-Gordon system that naturally appear in all kink-antikink collisions. Conversely, the collision of two topological radiative solutions can result in the creation of a kink-antikink pair.Design of biological detector based on human chromosome
https://jrmbs.scu.ac.ir/article_19513.html
We investigated biosensors based on the human chromosome (CH22 sequence. The results show that the electronic and spin transfer of the CH22 sequence is strongly dependent on the frequency and amplitude of incident light and mechanical stress. Accordingly, within the specified frequency domain of 4 to 5 terahertz (THz), the system demonstrates the CH22 capability to transfer the maximum electric current. Furthermore, upon the application of longitudinal stress quantified strain which is denoted by (S1=4), it is observed that the system facilitates the transmission of the maximal spin current. Furthermore, this study shows the emergence of a region of negative differential resistance in response to bias voltage changes, a phenomenon that does not occur in the absence of incident light and DNA tilt, even when mechanical stress is applied. Also, the results showed that positive mechanical stress has a better effect on the formation of spin flow than negative stress. Medical diagnostic tools based on spin polarization have a special place in medicine. By accurately controlling the parameters affecting electrical and spin transport, these sensors can detect biomolecular changes with high sensitivity in biological environments, which can create a fundamental change in the design of modern medical monitoring systems.