International Journal of Modern Physics B最新文献

In this paper, using density functional theory (DFT), we present a systematic computational investigation on ZrCl₄ in respect of electronic, structural, optical, mechanical properties, which is of great interest in semiconductor physics. Our results show that the metal tetrachloride is a mechanically stable semiconductor with a wide indirect bandgap of $E_g^{\mathrm{\text{HSE}}03}=4.82$$$eV ($E_g^{\mathrm{\text{GGA}}}=3.56$$$eV). ZrCl₄ could behave as a brittle material and could be covalent. According to our optical data, a reflectivity of 27.6% could suggest a good material absorption characteristic on the studied material, with a high absorption coefficient of up to $1.61\times 10^5$$$cm${}^{-1}$. On the partial density of states plot, the hybridization of electron orbitals between Cl 3p⁵ states in the valence band and transition Zr 4d² states in the conduction band is also observed. Our findings advance the fundamental understanding of ZrCl₄ material and provide important insights in electronic/optoelectronic applications.

Artificial neural circuits can effectively reproduce the main biophysical properties of neurons when reliable electronic components with unique physical properties are introduced. Connecting memristor to neural circuits not only enhances the potential controllability under external physical stimuli but also recognizes the effects of electromagnetic induction on neural activity. In this paper, the piezoelectric ceramic and memristor are embedded in FitzHugh-Nagumo (FHN) neural circuit, then two kinds of functional neuron models with magnetic field-control and electric field-control are obtained, respectively, to estimate the effects of external sound waves and external electric fields. To investigate the energy consumption when information transfer between neurons, the Hamilton energy functions of the above neuron models are obtained by calculating the field energy of each electronic component, and their correctness is verified by Helmholtz’s theorem. In addition, two neurons can be coupled by an induction coil to equal the processing of chemical coupling and realize pumping energy between neurons. Moreover, an energy switch is added to the coupling channel to open or close the coupling channel by detecting the diversity of energy. That is, it is kept open when the coupled system is exchanging field energy until the energy diversity between neurons is controlled at a limited threshold. The two-parameter bifurcation results show that the above two neurons have different bifurcation modes under different external magnetic or electric fields. For coupled systems, it is found that two identical neurons can achieve complete synchronization (energy balance) or intermittent complete synchronization (intermittent energy balance) by adaptive coupling. However, two diverse neurons can only achieve phase lock or phase synchronization, since the diversity of the coupled system parameters can disrupt the achievement of complete synchronization. These results are helpful for designing intelligent neural networks by taming the coupling channels with gradient energy distribution.

The analysis of non-Newtonian fluid flow over an oscillating surface often involves numerical simulations and experimental investigations. Computational fluid dynamics method including finite difference or finite element techniques can be used to crack the governing equations of the fluid flow. In this work, we used the Crank–Nicolson numerical technique to analyze the numerical behavior of unsteady boundary layer flow of Casson fluid with natural convection past an oscillating vertical plate. The temperature-dependent viscosity is assumed for the flow analysis. The impact of chemical reaction and heat generation coefficient is used to examine the mass and heat transferal rates. The investigation of non-Newtonian fluid flow over an oscillating surface is crucial for a wide range of industrial, biomedical, and scientific applications. The governing model of equations occurs in the form of nondimensional PDEs and then we use the dimensionless variables in order to achieve the dimensional PDEs. These equations are numerically solved by using the Crank–Nicolson technique. The Crank–Nicolson scheme is used because it has the ability to provide accurate and stable solutions and make it a valuable numerical technique in various scientific and engineering disciplines. The findings indicate the significance of numerous parameters on the mass, velocity and energy regions. The numerical outcomes of skin friction are observed due to fluid parameter, viscosity parameter, Grashof numbers of heat and solutal rates.

Open quantum systems are a subject of immense interest as their understanding is crucial in the implementation of modern quantum technologies. In the study of their dynamics, the role of the initial system–environment correlations is commonly ignored. In this work, to gain insights into the role of these correlations, we solve an exactly solvable model of a single two-level system interacting with a spin environment, with the initial system state prepared by a suitable unitary operation. By solving the dynamics exactly for arbitrary system–environment coupling strength while taking into account the initial system–environment correlations, we show that the effect of the initial correlations is, in general, very significant and nontrivial. To further highlight the importance of the initial system–environment correlations, we also extend our study to investigate the dynamics of the entanglement between two two-level systems interacting with a common spin environment.

Using Eu₂O₃, BaCO₃, Si₃N₄ and SiO₂ as starting materials, we succeeded in synthesizing BaSi₄O₆N₂:Eu${}^{2+}$ by firing the mixture at 1100^∘C for 2$$h in a reducing atmosphere (N₂(95%)–H₂(5%)). As a result, a single phase was obtained by setting the charge composition ratio to Si/$\mathrm{\text{Ba}}=6$. When the Eu${}^{2+}$ activation amount was 1%, it showed a broad emission in the range of 400–600$$nm under the excitation light of ultraviolet rays at 320$$nm. This phosphor exhibited chromaticity coordinates of $(x,y)=(0.258,0.297)$ under irradiation with ultraviolet rays at 320$$nm and is thought to be a promising phosphor for ultraviolet-excited white LEDs.