نشریه پژوهش سیستم های بس ذره ای
سال یازدهم شماره 4 (پیاپی 31، زمستان 1400)

In this paper, a new two-dimensional nanostructure called germanium sulfur diphosphide (GeP2S) structure, in the framework of the Density Functional Theory (DFT) has been predicted. In addition to studying the static and dynamic stability; structural properties of this two-dimensional nanostructure have also been compared with similar previous structures. The research findings indicate the acceptable stability of the proposed monolayer. The electronic aspects of this monolayer in the optimal state have been investigated and presented by two methods of hybrid function approximation (HSE06) and generalized gradient approximation method (GGA-PBE). The study of electron properties of this proposed monolayer introduces it as an indirect semiconductor with an energy gap of 1.367 eV by the HSE06 approximation and 0.688 eV by PBE-GGA approximation method. Study of optical properties of this proposed nanostructure indicate the agreement of optical band gap with the electronic band gap of this two-dimensional monolayer, especially in the HSE06 approximation method. Based on the findings of this study, due to the relatively high absorption rate and very low reflectivity in the visible spectrum in the energy range of 1 to 5 eV, if this proposed nanostructure is synthesized can be considered suitable for optical applications, especially in solar energy devices.

In this study by Using the di-nuclear systems model (DNS), the evaporation residue cross-section of two cold fusion reactions 64Ni+208Pb and 64Ni+209Bi is calculated. ،The nuclear proximity potential is used for interaction between nuclei. In these calculations thermodynamic quantities of compound nuclei such as temperature and heat capacity are obtained using Ginzburg- Landau (EGL) theory and temperature dependent back shifted Fermi gas model (TDP- BSFGM). The obtained results of cross section are compared with experimental data and other data that is obtained using another model. Also, the plot of heat capacity versus temperature has a S-shape form which is indicator of breaking of the nucleonic pairs.

n this paper, it has been shown that the doped disk-like quantum dot with Gaussian impurity can operate as an optical rectifier. The simultaneous presence of impurity and the external electric field in the quantum dot causes to an asymmetric structure. The asymmetric quantum dot can exhibit the significant nonlinear optical properties such as optical rectification. Also, it has been shown that the value of the optical rectification can be controlled by the external field and the Gaussian impurity parameters (strength, decay length and impurity position in the quantum dot). The results of the numerical calculations represent that the optical rectification value of doped quantum dot with the repulsive impurity is stronger than the attractive impurity. Furthermore, the study of the effect of strength and direction of the applied electric field on the optical rectification shows that enhancement of the electric field strength causes to more confinement. Therefore, the optical rectification value decreases, when the value of electric field increases.

In this study, we introduce a new class of two-mode qutrit-like entangled states based on the `Near' coherent states. They link to a specific class of non-classical states, namely, photon added coherent states, which makes them capable candidates in quantum information processes. Based on these states, various superpositions such as the two-qubit entangled states, have been introduced and studied by various authorities, which is evidence for their valuable quantum properties. Therefore, based on the above-mentioned relationship and the emergence of controllable non-classical properties of these states, in this work, we seek to analyze the effect of adding photons to two-qutrit entangled states. For this purpose, we present a general analysis of non-classical properties such as the photon statistics and entanglement with emphases on the control role of the shift parameter of these states. We apply the generalized I-concurrence measure to quantify the entanglement and the condition in which quantum entanglement can be enhanced and maximized. Comparing with some cases already discussed in the literature, we can see that the photon addition, which is equivalent to selecting a specific shift parameter, plays an important role in non-classical effects, and this operation can be applied to enhance and preserve the entanglement.

As a new family of 2D materials, transition metal carbides and nitrides (MXenes) have attracted growing attention in recent years due to their widespread potential applications. In this study, the electronic structures and optical properties of MXenes M2CF2 (M=Y, Lu) have been investigated using density functional theory (DFT) calculations. Based on the results, the Y2CF2 (Lu2CF2) monolayer is a semiconductor with indirect bandgap of 1.67 eV (1.42eV). Comparing the electronic bandgap of Y2CF2 and Y2CCl2 demonstrates the dependency of electronic and optical properties of these materials to the surface termination taking place during the experimental preparation of MXenes. To study the optical properties, the real and imaginary parts of the dielectric function was calculated. According to the results, there is a remarkable absorption in the ultraviolet and visible regions that they have better absorption compared to that of BP, MoS2 and Sc2CO2 monolayer compositions in the visible region. We have also considered electron energy loss function, refractive index and optical conductivity of the structures. All obtained results express that M2CF2 (M=Y, Lu) monolayers are good candidates for electronic, optoelectronic and solar energy applications.

In the present work, formation of self-organized periodic nanostructures (SPN) in photosensitive thick (h ~ 270 nm) slab waveguide AgCl films doped by silver nanoparticles is studied. The SPN is formed as a result of interaction of a elliptically polarized light, incident light, with the AgCl-Ag layer. Formation of such nanostructure induces in the film an optical activity, which is due to the induced anisotropy and the chirality of the formed structure. The greater thickness of the layer results in excitation of higher mode TE1 of the slab waveguide which leads to simultaneous formation of two SPN associated with TE0 and TE1 modes, accordingly. It is shown that, irradiation by elliptically polarized light results in more complicated SPN with enhanced chirality, which creates stronger induced optical activity of the samples.

In this work, the linear and nonlinear optical properties of the Schiff base N,N'-bis(2-hydroxybenzylidene) benzidine (HBB) will be investigated by two methods, Z-scan technique and quantum mechanical calculations. For this purpose, first, the absorption spectrum of HBB compound in DMSO, DMF, CH3Cl is prepared and the effect of solvent polarity on their bandgap energy is investigated. The results show that the dissolved sample in DMSO has better nonlinear properties than other samples. Then, the nonlinear properties of the sample are calculated by the Z-scan technique. The values of the nonlinear refractive index, nonlinear absorption coefficient and third order susceptibility of the sample in DMSO solvent are 0.10810-10 cm2/W, 0.1436110-6 cm/W and 4.43710-9 esu respectively. Also, the quantum mechanical analysis will be used for calculating the dipole moment (), the dipole polarizability (), and also the second and third nonlinear molecular hyperpolarizabilities (β and γ). Both experimental and theoretical results show that the HBB has a high nonlinear potential and can be a good candidate for optical devices.

Phosphine (PH3) is a toxic and harmful gas and is released by the reaction of aluminum phosphide or rice pill in the presence of water, water vapor or stomach acid. Poisoning caused by phosphine is more suicidal and two thirds of the poisoned ones die. In this paper, density functional theory has been used to investigat the structural and electronic properties of (10,0) BC3 and SiC nanotube. The PH3 molecule has been first placed at the equilibrium distance which is about the sum of atomic radius of B/C/Si of nanotube and P/H of phosphine molecule, inside and outside the nanotube from both H and P atom sides. Then the structure has been completely relaxed and the electronic calculations have been performed on relaxed structures. Considerable alternations are observed in electronic properties of BC3 nanotube which show that this nanotube is potentially a good candidate for detecting and adsorbing PH3 molecules. Partial densities of state calculations were also performed to find the origin of each adsorption.

In this study, the structural, electronic and transport properties of the (5, 0) zig-zag BN, GaAs, GaN, GaP, InN and InP nanotubes have been studied using Density Functional Theory (DFT) combined with Non-Equilibrium Green’s Function (NEGF) formalism with SIESTA software. The electronic band structure, density of states (DOS), current-voltage (I-V) characteristics and quantum conductance curves (dI/dV) of these structures were studied under low-bias conditions. The obtained results demonstrate that all of these structures exhibit semiconducting behavior but the (5, 0) zig-zag GaP nanotube has an indirect band gap which makes it suitable to use for full color displays. Instead the (5, 0) zig-zag GaAs nanotube has a smaller band gap, the highest value of the electron density of states and it showed the amazing property of Negative Differential Resistance (NDR). Therefore, it is an important candidate to use in high-speed optoelectronic devices, high-speed switching devices and high frequency oscillators.

The absorption of fluorine on the graphene surface controls the energy gap. As a result, fluorinated graphene can be a valuable material for electronic applications. Based on molecular dynamics (MD) simulations, the effect of concentration and temperature on the absorption process of fluorine atoms on the graphene surface is investigated. Results show that the number of fluorine atoms absorbed on the graphene surface increases to a certain amount with the concentration of atomic fluorine gas. Further increases in atomic concentration show no effect. The number of C-F bonds increases by temperature so that the structure of the graphene is not disturbed. The adsorbed-fluorine atoms are arranged in a manner that compensates for the imbalance between the two sublattices.

In this study, one-dimensional MnO2 nanostructures such as nanorods, nanotubes, and nanowires have been synthesized by the hydrothermal method. MnO2 nanostructures have been characterized by x-ray diffraction, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and meter LCR.The results of the XRD show that MnO2 nanostructures are single phase. Also, the SEM images well shows the nanostructures such as nanorods, nanotubes, and nanowires have been formed. The LCR meter results show that the dielectric constant and dielectric loss at the low frequencies are due to high electrical resistance at the grains boundaries while at the high frequencies are due to small electrical resistance at the grains with electrical resistance is low. The ac electric conductivity of the -MnO2 nanostructures by increasing frequency, have been increased that this increase are due to the hopping process between 〖Mn〗^(3+)/〖Mn〗^(4+).

This paper analyses the effects of an extended microstructure in the microscopic discretion of spacetime. In this setup, all point structures get replaced by smeared distributions owing to this extended microstructure. We investigate the effect that such a modification of point mass and charge has on the thermodynamics of a charged anti-de Sitter black hole. In addition, the modification of point structures by smeared distributions modifies the energy of the black hole. The effects of such a deformation in the macroscopic geometry are studied by using the local equipartition of energy and the holographic principle. Thus, it is possible to obtain the corrections to the entropic force from such a deformation of the theory. This will in turn modify the Newton's gravity law in the Verlinde formalism.