Modern Physics Letters B

First-principles simulations are conducted to explore the structural stability, electronic properties, and optical responses of pristine and boron- or nitrogen-doped monolayers graphene. The computed electronic density of states revealed that the substitutional doping of boron impurity atoms on monolayer graphene (MLG) shifts the Dirac point upward, although the substitution of nitrogen impurity atoms in graphene pushes the Dirac point downward the Fermi level. This could exhibit that upon the doping of MLG with boron or nitrogen, respectively, p-type or n-type semimetal is acquired. The overall optical spectral properties of the substituted graphene with boron or nitrogen atoms are simulated and compared with the optical spectra results of pure graphene. The optical features of pristine and doped MLG are determined by taking the interband and intra-band transitions into account ranging from the far-infrared to the ultraviolet regime of the electromagnetic radiation. A remarkable red shift in the optical spectra of the doped MLG towards the visible regime of radiation is established. An enhanced reflectivity illustrated that concentration-dependent optical properties of boron and nitrogen-doped MLG happen at lower electromagnetic radiation regimes. In addition, we explored the thermoelectric behaviors of the pristine/doped graphene monolayers with $4\times 4$ supercells. We found a significant improvement in the electrical conductivity of graphene when doped with boron or nitrogen impurities. However, an increase in the electrical conductivity has textured a decrease in the Seebeck coefficients. Improvement in the electrical conductivity is attributed to an interesting effect on the graphene monolayers’ power factor (PF). These findings indicate a positive impact of the dopants on the thermoelectric properties of graphene monolayers and reveal that they are potential materials for thermoelectric applications and nanodevices.

Solving differential equations is an ancient and very important research topic in theory and practice. The exact analytical solution to differential equations can describe various physical phenomena such as vibration and propagation wave. In this paper, the bilinear neural network method (BNNM), which uses neural network to unify all kinds of classical test function methods, is employed to obtain some new exact analytical solutions of the ($3+1$)-dimensional Hirota bilinear (HB) equation. Based on the Hirota form of the HB equation, we constructed four kinds of new solutions which contain the breather solution, rogue wave solution, breather lump-type soliton solution and the interaction solution between the periodic waves and two-kink wave by introducing a series of test functions in both single-layer and multi-layer neurons such as [4–2–2] and [4–2–3] neural network models. In addition, we compared them to those that had already been published. It is clear that our results are not consistent with those found in these publications. Their corresponding dynamic features are vividly demonstrated in some 3D, contour, x-curves and y-curves plots. The results obtained demonstrate the potential of the proposed methods to solve other nonlinear partial differential equations in fields.

This study investigated fluid flow and forced convective heat transfer in rectangular microchannels with square barriers, as illustrated in Fig. . In the first situation, three obstacles were positioned along the microchannel’s top wall. In the second scenario, obstacles were positioned along the microchannel’s bottom wall. In the final example, three square obstacles are placed symmetrically on either side of the microchannel wall. With the help of the Finite Element Method (FEM), we investigate the physicochemical behavior of the microchannel. The development of computer code within COMSOL multiphysics made it possible to simulate heat transport and fluid flow. The results include the implications of the rarefaction effect on fluid flow and heat transmission and decisions regarding the location of barriers and the shape of obstacles in squares. In addition, with the lowest value in skin friction and a lower Nusselt number, the third example, which has barriers on both sides, provides a valuable method for reducing the fluid temperature at the exit of the microchannel. This is because it has barriers on both sides. In the section under “Results and Discussion,” we provide an in-depth analysis of the numerical data derived from the microchannel.

• •Objective: This study aims to numerically investigate forced convective heat transfer in a rectangular channel featuring multiple square obstacles. The simulation employs the FEM to model fluid flow and temperature distribution.
• •Geometry and complexity: The channel geometry incorporates square obstacles, introducing geometric complexity. The FEM is chosen for its capability to handle intricate geometries accurately.

This paper intends to discuss the hybrid nanofluid flow through a cone in a Darcy–Forchheimer porous media, containing base fluid Methanol (CH₃OH), nanoparticles of titanium oxide (TiO₂) and copper (Cu). We have examined the flow under the influences of mixed convection, viscous dissipation, chemical reaction, and nonlinear heat source. In hybrid nanofluid flow, viscous dissipation and mixed convection play a crucial role in heat exchangers. By accounting for both mixed convection and viscous dissipation, the addition of nanoparticles into a base fluid improves the transfer of heat and optimizes the performance of the cooling system. Using the laws of conservation, governing equations have been constructed. The flow model is converted using the appropriate similarity transformations from partial differential equations to ordinary differential equations. The homotopy analysis method is used to solve the updated system of equations. When Forchheimer inertial drag parameter is increased, the velocity profile decreases, but it rises when the Darcy number is increased. As the value of exponential heat source parameter rises, the temperature profile increases as well. The result exposes that with an increment in nanoparticle volume fraction, temperature profile also rises but velocity profile decreases.

In this paper, a TMDC-based surface plasmon resonance (SPR) sensor for detecting fat concentration milk, incorporating an Ag-Pt (bimetallic) layer, is presented. The Pt (Platinum) layer provides chemical stability and increases sensitivity with the TMDC layer. Compared to the conventional SPR sensor, the maximum sensitivity, detection accuracy (DA), and figure of merit (FoM) of 314^∘/RIU, 0.142/degree, and FoM 44.05/RIU are achieved with the WS₂ layer. The sensor’s increased sensitivity is due to the increased field intensity and depth of penetration into the sensor layer, resulting in a larger interaction volume. The presence of the WS₂ layer, with its significant imaginary part of the dielectric constant, helps improve sensitivity and broadens the SPR curves. This broadening SPR curve ultimately affects the DA and FoM of the sensor. The capability of the proposed sensor to detect various biological analytes with a refractive index (1.3452–1.3657) can be demonstrated.

As the core of reproducing the real nonlinear phenomena of traffic congestion, the investigation of car-following models, which take into account human factors, has consistently assumed a central role within the domain of transportation science. Nevertheless, it is noteworthy that prior studies have invariably employed a fixed value for driver reaction time to stimuli, whereas it is imperative to recognize the dynamic nature of this parameter, closely associated with the instantaneous vehicle speed. To address this issue, this paper constructs a dynamic sensitivity coefficient (DSC), and further develops a nonlinear human factoring car-following model to reveal the relation between the reaction time and the current speed. Firstly, the linear critical stability condition and the mKdV equation of the model are derived by the linear stability analysis and kink–antikink solution analytic method, respectively. Then, the numerical experiments are conducted to demonstrate that the proposed model is more practical and can reproduce the real driving behavior and phenomena. Finally, calibration and validation results exhibit the actual vehicle trajectory can be simulated well.

All layers of MASnI₂Br-based perovskite solar cells (PSCs) were deposited by ultrasonic spray pyrolysis method. The depositions of the layers were carried out in a large area. The perovskite thin film deposited on FTO/TiO₂ had large grains. The crystallite size of the film was calculated as 90nm from the XRD pattern. The bandgap of 1.54eV was determined from the UV-visible measurement of MASnI₂Br thin film. The PSCs with the different active areas (0.3cm² and 3.18cm²) were fabricated. The champion cells’ power conversion efficiencies were recorded at 0.181% and 0.120% for 0.3cm² and 3.18cm², respectively.

This work aims to investigate the structural stability, magnetic and electronic properties of M₃AlC antiperovskites using density functional theory (DFT) and Monte Carlo simulation. The obtained ground state results reveal that the antiperovskites M₃AlC are stable in the ferromagnetic (FM) state with a metallic character. The calculated total magnetic moments are 5.21${\mu }_B$ and 3.34${\mu }_B$ for Mn₃AlC and Fe₃AlC, respectively, with the total moments mainly from the M atom. The ferromagnetic behavior is confirmed by computing the density of state at Fermi level and verified the Stoner criterion. The magnetic and magnetocaloric behavior of M₃AlC is investigated using Monte Carlo simulation and the obtained results demonstrate that the transition from ferromagnetic to paramagnetic state occurs at $T_C=300$K and $T_C=230$K for Mn₃AlC and Fe₃AlC, respectively. These values of $T_C$ are in good agreement with the experimental results. The magnetocaloric effect and critical behavior are studied and the obtained values of magnetic entropy change $|\mathrm{\Delta }{S}_{\mathrm{\text{mag}}}|$ at 4.5T is about 4.242J/kg.K and 3.666J/kg.K and the relative cooling power (RCP) are 342.434J/kg.K and 325.26J/kg.K for Mn₃AlC and Fe₃AlC at 4.5T, indicating that these compounds are more appropriate for magnetic refrigeration. Finally, the critical exponents ($\beta$,$\gamma$,$\delta$) are calculated and the obtained values are close to the values of mean-field model.

The electronic intrinsic surface states in wurtzite Zn-IV-N₂ (with group-$\mathrm{\text{IV}}=\mathrm{\text{Sn}}$, Ge and Si) semiconductors were investigated using an intermediate-coupling variational approach considering the electron–surface optical phonon interaction influence. The intrinsic surface state energy distribution and the average penetrating depth of surface state eigen-wave function of the electron have been evaluated numerically by changing the surface potential barrier $V_0$ for wurtzite ZnSnN₂, ZnGeN₂ and ZnSiN₂, respectively. The results show that the electronic intrinsic surface state energy increased linearly with increasing surface potential barrier $V_0$ for all the calculated materials. The result also indicated that the electronic intrinsic surface state energies variations due to the influence of electron–surface optical phonon interaction are dozens ofmeV. The average penetrating depth of electronic surface state eigen-wave function is independent of $V_0$. Its value is no more than the corresponding material’s lattice constant. The electronic scattering by surface optical phonon should be taken into account in the study of the intrinsic surface state of electrons in the group of Zn-IV-nitrides (with $\mathrm{\text{IV}}=\mathrm{\text{Sn}}$, Ge and Si) semiconductors, especially for materials having strong electron–phonon interaction and wide band gap.

Due to their distinct characteristics and prospective uses in several disciplines, half-Heusler (HH) materials are a family of intermetallic compounds that have garnered a lot of attention. HH compounds have a cubic crystal structure and exhibit a wide range of electronic, optical, mechanical and thermoelectric characteristics. Direct bandgap acquired by the WC-GGA (TB$+$mBJ) approach is 1.07eV (2.26eV), 0.61eV (1.71eV), 0.76eV (1.68eV), and 0eV (0.78eV) for KMgP, KMgAs, KMgSb, and KMgBi, respectively. Threshold power ${\epsilon }_2(\omega )$ of KMgX ($X=\mathrm{\text{P}}$, As, Sb, and Bi), starts from 2.218, 1.701, 1.674, and 0.776eV, so they exhibit the distinct peaks at 4.014, 3.742, 3.388, and 3.197eV, correspondingly. Among these materials, the maximum value of Seebeck coefficient (S) has been attained at 300K. Specifically, KMgP achieves the highest value of S at 3.134mV/K, followed by KMgAs at 2.947mV/K, KMgSb at 2.893mV/K, and KMgBi at 1.431mV/K, all in their respective p-type configurations. In order to determine the compound’s stability, we will explore the elastic and thermodynamic properties. We will also discuss their possible applications in photovoltaic and thermoelectric devices.

In this paper, we investigated the sign-of-coupling dependence of the von Neumann Entanglement Entropy (EE) between system and environment in the ground state of networks of N coupled quantum oscillators. We find that whether the EE increases or decreases with the amplitude of coupling strengths between particles depends on the repulsive or attractive nature of the couplings, and it also depends on whether the coupling is between system-environment or particles both in the environment. In particular, the EE decreases with the amplitude of an attractive coupling between particles both in the environment. We also find that the EE varies nonmonotonically with number of particles directly interacting with the system with attractive couplings; besides, the position-momentum uncertainty of the particle in the system and the EE vary contrarily when the particle-number is small.

This study aims to investigate the modified nonlinear time fractional Harry Dym equation using analytical and numerical techniques. The modified nonlinear time fractional Harry Dym equation is a generalization of the classical Harry Dym equation, which describes the propagation of nonlinear waves in a variety of physical systems. The conformable fractional derivative is used to define the time fractional derivative in the equation, which provides a natural and straightforward approach. The Khater II method, a powerful analytical technique, is employed to obtain approximate solutions for the equation. Additionally, three numerical schemes, namely, Cubic-B-spline, Quantic-B-spline and Septic-B-spline schemes, are developed and implemented to solve the equation numerically. The numerical results are compared with other numerical solutions to assess the accuracy and efficiency of the proposed schemes. The physical meaning of the modified nonlinear time fractional Harry Dym equation is discussed in detail, and its relation to other nonlinear evolution equations is highlighted. The results of this study provide new insights into the behavior of nonlinear waves in physical systems and contribute to a better understanding of the physical characterizations of the modified nonlinear time fractional Harry Dym equation.