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.