Vol. 68 No. 6 Nov-Dec (2022): Revista Mexicana de Física

In this paper, the energy levels of the ground-state band (GSB) and other states for 114−128Cd isotopes have been determined using the Interacting Boson Model (IBM-1) with a New Empirical Equation (NEE). The GSB results showed that the IBM-1, NEE, and available experimental data were all in fairly consistent. The NEE and IBM-1 calculations for the high states above 6+ state are slightly overestimated compared to the experimental data, with the exception of the 114Cd and 118Cd nuclei. Furthermore, the reduced transition probabilities B(E2) extracted from the IBM-1 model agree well with the available experimental data. The potential energy surface (EPS) was also examined with the IBM-1. The EPS contour results for Cd isotopes demonstrate that the Cd isotopes under investigation represent a smooth transition behavior from light Cd nuclei toward a more collective vibrational mode as the neutron number increases.

We perform a numerical study of the unitary regime as a function of disorder concentration in the imaginary part of the elastic scattering cross-section for the compound Sr2RuO4 in the flat band non-disperse limit. By using a self-consistent tight binding (TB) method, we find a couple of families of Wigner probabilistic functions that help to explain macroscopically the distribution between Fermion dressed quasiparticles and Cooper pairs, and also the position of nodes in the order parameter for Sr2RuO4. Therefore, we are able to show that a TB model for the FS γ-sheet, numerically shows 4 point nodes in a flat γ sheet limit, or 4 quasi-point nodes for strong dispersion γ sheet limit in the reduced phase scattering space (RPS).

The structural, elastic, electronic and thermodynamic properties as well as the magnetism of the ternary full-Heusler alloys Rh₂MnZ (X = Sn, Pb and Tl) have been investigated by using full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT) within the generalized gradient approximation (GGA). The AlCu₂Mn-type structure is energetically more favorable than the CuHg₂Ti-type structure for all the compounds studied here and found to be are ferromagnetic. The electronic structures calculations are found to exhibit a metallic character for all the herein studied compounds Rh₂MnZ (X = Sn, Pb and Tl) alloys. The magnetic properties reveal that the Mn atom is responsible for large magnetic moment. Moreover, the mechanical behavior shows that all studied compounds are mechanically stable, ductile and anisotopic in nature. The elastic and thermodynamic properties for Rh₂MnTl compound have not yet been established. The obtained results for various properties of the series of Rh₂MnZ (X = Sn, Pb and Tl) are compared with those found experimentally and theoretically.

In this work, we theoretically and experimentally study the issue of the spontaneous capillary rise of a viscous liquid in wedge-shaped tilted cells, with very short angles of aperture, α. We provide the equilibrium profiles yse and, by means of the Reynolds lubrication equations, we find the time-dependent profiles and the dynamic evolution of the meniscus close to the edge of the wedge, as a function of time, which follow power laws of the form ys ∼ t 1/3 . Experiments performed at various inclinations are consistent with our theoretical results.

In this paper we consider the discrete heat equation with a certain non-uniform space interval which is related to q-addition appearing in the non-extensive entropy theory. By taking the continuous limit, we obtain the q-deformed heat equation. Similarly, we obtain the solution of the q-deformed diffusion equation

We consider two semi-infinite magnetoelectric media with constant dielectric permittivity separated by a planar interface, whose electromagnetic response is described by non-dynamical axion electrodynamics and investigate the radiation of a point-like electric dipole located perpendicularly to the interface. We start from the exact Green's function for the electromagnetic potential, whose far-field approximation is obtained using a modified steepest descent approximation. We compute  the angular distribution of the radiation and the total radiated power finding different interference patterns, depending on the relative position dipole-observer, and polarization mixing effects which are all absent in the standard dipole radiation. They are a manifestation of the magnetoelectric effect induced by axion electrodynamics. We illustrate our findings with some numerical estimations employing realistic media as well as some hypothetical choices in order to illuminate the effects of the magnetoelectric coupling which is usually very small.

We investigate the kinematics of the motion of an observer with constant proper acceleration (relativistic hyperbolic motion) in 1+1 and 1+3 dimensional Minkowski spacetimes. We provide explicit formulas for all the kinematic quantities up to the fourth proper time derivative (the Snap). In the 1 + 3 case, following a recent work of Pons and de Palol [Gen. Rel. Grav. 51 (2019) 80], a vectorial differential equation for the acceleration is obtained which by considering constant proper acceleration is turned into a nonlinear second order differential equation in terms of derivatives of the radius vector. If, furthermore, the velocity is parameterized in terms of hyperbolic functions, one obtains a differential equation to solve for the argument f(s) of the velocity. Differently from Pons and de Palol, who employed the particular solution, linear in the proper time s, we obtain the general solution and use it to work out more general expressions for the kinematical quantities. As a byproduct, we obtain a class of modified Rindler hyperbolic worldlines characterized by supplementary contributions to the components of the kinematical quantities.

In the non-relativistic quark model, the interaction potential for the tetraquark is proposed which involves the logarithmic potential, linear potential, harmonic potential, and spin-spin interaction potential. Analytically, the non-relativistic Bethe-Salpeter equation is solved, with diquark-antidiquark congurations taken into account. The work iscompared to other recent works. Our results of the heavy tetraquark may provide useful information for future experimental data.

In this work we study the effects of Initial State Radiation (ISR) and Beamstrahlung (BS), in the production of Z 0 in the 3-3-1 model with heavy leptons. The impact of the ISR and BS on precision measurements strongly afects the behaviour of the production cross section around the resonance points: mZ0 = 5976.43(6830.21; 8539.47) GeV for vχ = 3.5(4.0; 5.0) TeV, at the Compact Linear Collider (CLIC).

In this study, we have investigated the structural, electronic, and elastic properties of a new series of Os₂YAl, (Y=Sc, Ti, V) alloys called "Full Heusler", based on the Wien2k code using the functional density theory (DFT). The exchange and correlation energy are evaluated as part of the LDA approximation.  The results showed that Os₂VAl was more stable and harder than Os₂ScAl, and Os₂TiAl. The electronic band structures and density of states (DOS) of the compounds indicate that they are metallic because there is no bandgap in these three materials these results have been shown by three approaches (LDA, TB-mBJ, and SOC). Near the Fermi level, the energy is mainly occupied by the Os-5d and Sc, Ti, V-3d electrons. According to the results of the second-order elastic constants, these compounds met Born's criteria for mechanical stability. The elastic properties indicate that our compounds are ductile, anisotropic, and rigid. All the calculations and the data were compared with the results obtained with different methods in terms of its mechanical and electronic behavior, Os₂VAl was found to have better physical properties than Os₂ScAl, and Os₂TiAl.

The requirements of high quality factor, low power consumption, easy design techniques and compatibility with the main standard fabrication processes of integrated circuits (IC) make the tunable piezoelectric resonators a suitable option for the new technologies of fifth generation of telecommunication (5G) and Internet of Things (IoT). In this work the nonlinear state equations for piezoelectric effect are presented. From these equations we may deduce which materials can be used in applications where a hysteresis behavior or resonance frequency tunability are required, additionally, it is shown which crystals have the nonlinear tensor’s symmetry compatible with each application field. A novel model for the tunable piezoelectric devices is shown taking into account the consequences of voltage tuning. Finally, three different ways to design and implement the nonlinear behavior of piezoelectric materials to tune devices are introduced.

In this paper, we studied the structural, electronic and some optical properties of KGaQ2 (Q = S, Se) and AGaTe2 (A = K, Cs) crystals using the pseudopotential plane-wave (PP-PW) method based on density functional theory (DFT), the generalized gradient approximation (GGA) parameterized by Perdew-Burke-Ernzerhof (GGA-PBE) is used for the exchange – correlation (XC) potential. We also use the hybrid density functional (HSE06) to study the electronic structures of these materials. Our results for the equilibrium lattice constants (a, b and c), angle β are in good agreement with experiment data. The electronic structure calculation suggested that crystals are direct-gap semiconductors, employing both the Perdew–Burke–Ernzerhof (PBE) and the hybrid (HSE06) functionals. We note that the hybrid density functional improved the value of band gap, and that the studied compounds are semiconductors with wide band gaps.  We have also predicted the optical properties; the refractive index, the reflection coefficient and dielectric constant on high frequencies.

Density functional theory (DFT) was applied to investigate the structural, electronic, elastic, magnetic, thermodynamic and half-metallic properties of the newly d⁰ Heusler alloys (HAs) CsCaZ (Z= Ge, Sn and Pb). Spin-polarised calculations show that  the compounds studied are half-metallic with a magnetic moment of 1.00 μB at the equilibrium lattice parameter, which obeys the well-known Slater–Pauling rule M_tot = 8 – Zt. The half-metallic behavior of the compounds CsCaGe, CsCaSn and CsCaPb is predicted with respect to the equilibrium lattice constants for CsCaGe, CsCaSn and CsCaPb with a narrow band gap in the majority spin channel. Furthermore, the elastic constants (Cij) showed that these materials are ductile and anisotropic. In addition, the negative values of the calculated formation energy and cohesion energy indicate that CsCaZ (Z= Ge, Sn and Pb) are likely to be experimentally synthesized. Non-equilibrium Gibbs function is employed to calculate the thermodynamic properties through the quasi-harmonic Debye model in which the bulk modulus, heat capacity, Debye temperature, thermal expansion coefficient, and entropy are investigated at 0-20 Gpa pressure and 0-1200 K temperature ranges. The significant half-metallic behavior makes the CsCaZ (Z= Ge, Sn and Pb) compounds strong candidates for spintronic applications.

We discuss possible uncertainties in theoretical predictions for γd → π 0 d observables near threshold due to the use of different elementary γN → πN amplitudes using an approach which is based on time-ordered perturbation theory. Results are presented for unpolarized cross sections and all possible spin asymmetries of differential and total cross sections. Our results indicate that the estimations of the uncertainty on the γd → π 0 d observables show important sensitivity to the modeling of the elementary γN → πN operator. A comparison to presently available experimental data is given. The results presented here are of particular interest for the evaluation of the systematic uncertainties caused by the use of different elementary operators in the analyses of γd → π 0 d measurements to extract information on the free neutron amplitude from deuteron data.

In this study, we explain the impacts of nonlinearity and wave dispersion parameters on the soliton pulses of the (2+1)-dimensional Kundu–Mukherjee–Naskar equation (KMNE). In this regard, some new optical solitons are received via the unified method to the aforesaid equation to explain such impacts of the soliton pulses. The presenting optical solitons are expressed by the dark, periodic, bell, bright, kink, and singular soliton solutions. Taking into account the two impacts help stabilize the soliton pulses during their propagation by generating new dynamics depending upon the nonlinearity and the wave dispersion parameters of the studied equation. All the characteristics of the soliton pulses are exhibited graphically. It is found from the graphical outputs that the soliton profiles are decreasing and increasing with the increase of nonlinearity and dispersion parameters, respectively. The outcomes reveal that the soliton pulses are balanced due to the influences of nonlinearity and wave dispersion parameters of the aforementioned equation. It is mentioned that the impact of wave dispersion and nonlinearity parameters on the soliton pulses has not been discussed in the past. Therefore, the applied method permits the explanation of the various wave dynamics by analyzing the attained soliton solutions in nonlinear optical fibers systems, which can be used for further studies.

The single-electron transistor (SET) is one of the frontier device that can offer high operating speed at an ultra-low power consumption. SET macro-modeling, can be used for a SET-CMOS circuit simulation. In this work, we develop a new macro model of SET- CMOS hybrid whose is very useful effect in VLSI circuits design. All simulations are performed using environment SIMSCAPE of MATLAB SIMULINK. This architecture were realized by implementing the NMOS of conventional inverter with a SET macro-model. The simulation results show that the hybrid structure offers better performance. Indeed, the designed circuits are able to work at room temperature.

We have investigated the half Heusler compounds MNiBi (M=Sc, Y), using the framework of density functional theory DFT within the full potential linearized augmented plane wave (FP-LAPW) method and studied the structural, electronic, optical and elastic properties. The structural properties are predicted using the Generalized Gradient Approximation GGA and Local Density Approximation LDA, the calculations reveal that Lattice constants and other structural parameter are better matched in GGA approximation with experimental and theoretical result than LDA approximation. The calculated band structure and the density of states (DOS) with GGA, LDA and Tran and Blaha modified Becke-Johnson (TB-mBJ) exchange-correlation potentials, indicates a semiconducting nature with indirect narrow band gaps for both compounds ScNiBi and YNiBi, it shown from result that using (TB-mBJ) functionals is much more successful than the LDA and GGA approach in estimating bandgaps for our half Heusler ScNiBi and YNiBi. Optical properties of the compounds under investigation are also reported in this paper, high absorptivity are observed in the visible and ultraviolet region. The bulk modulus, shear modulus, young’s modulus, and other elastic constants are computed to discuss their elastic properties.

In this investigation thermochemical properties of 3-hydroxyphthalic anhydride were determined. Fusion enthalpy, fusion temperature and molar heat capacity in solid phase were obtained by differential scanning calorimetry. By the Knudsen effusion method, the molar enthalpy of sublimation at 298.15 K was obtained. By thermogravimetric data, it was possible to determine the molar enthalpy of sublimation and the molar enthalpy of vaporization. On the other hand, the molar enthalpy of formation in solid phase at 298.15 K was determined by combustion calorimetry. The molar enthalpy of formation in gas phase at 298.15 K was calculated from molar enthalpy of sublimation at 298.15 K and molar enthalpy of formation in solid phase at 298.15 K. This experimental value was compared both theoretical enthalpy of formation in gas phase by using Gaussian methods at the G3 and G4 levels and with an estimated value in relation to phthalic anhydride.

In this work an artificial neural network (ANN) was used to determine the pressure and internal energy equations of state of noble gases and some molecular liquids by predicting thermodynamic state variables like density and temperature encoded in the radial distribution function. The ANN is trained to predict the thermodynamic state variables using only the structural data. Then, predicted values are used to compute equations of state of real liquids such as argon, neon, krypton and xenon as well as some molecular liquids like nitrogen, carbon dioxide, methane and ethylene. In order to assess the ANN predictions the relative percentage error with the exact values were determined, showing that its magnitude is less than  1%. Thus, the comparison between equations of state computed with the predicted variables and experimental results exhibits a very good agreement for most of the liquids studied here. Since our ANN implementation only requires the microscopic structure as an input, data incoming from experiments, theoretical frameworks or simulations are suitable to perform predictions of state variables and with that complement the thermodynamic characterisation of liquids through the determination of equations of state. Moreover, further improvements or extensions related with the microscopic structure database can be safely addressed without changing the neural network architecture presented here.