International Journal of Modern Physics B

We study the s-wave quintet Cooper pairing phase (S_pair = 2) in spin-3/2 cold atomic systems and identify various novel features which do not appear in spin-1/2 pairing systems. A single quantum vortex is shown to be energetically less stable than a pair of half-quantum vortices. The half-quantum vortex exhibits the global analogue of the non-Abelian Alice string and SO(4) Cheshire charge in gauge theories. The non-Abelian half-quantum vortex loop enables topological generation of quantum entanglement.

We model DNA-cation complexes as infinite, one-dimensional, charged wires to single-out the interaction due to quantum fluctuations of the electric field from counterion-induced and water-related interactions. We obtain a frustration-free Casimir-like (codimension 2) interaction that extensive numerical analysis show to be a good candidate to explain the formation and stability of DNA aggregates.

The improved Tosi–Fumi pair potential has been employed to simulate the melting behavior and Grüneisen parameters of sodium chloride (NaCl) using molecular dynamics (MD) method at constant volume. The melting curve of NaCl is compared with the experimental data and other calculations in a pressure range from 0 to 144 GPa. The simulated results validate the amount of 20% superheating of the NaCl solid and yield an approximate power law dependence of the Grüneisen parameter (γ) on compression γ = γ₀(V/V₀)^q, with q ≈ 1.078, in the temperature range from 298 to 1073 K and pressure range from 0 to 60 GPa.

Pure nanocrystalline forsterite (Mg₂SiO₄) powder was successfully synthesized by mechanochemical route and subsequent annealing. The starting materials were talc (Mg₃Si₄ O₁₀(OH)₂) and magnesium carbonate (MgCO₃) powders. To produce forsterite powder, first talc and magnesium carbonate powders were calcined at 1200°C for 1 h and 700°C for 2 h, respectively. After that the mixture of obtained powders was milled by a planetary ball mill, and then annealed at 1000°C and 1200°C for 1 h. Thermogravimetric (TG) analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques were utilized to characterize the initial and prepared powders. The results showed that a single phase nanocrystalline forsterite powder with a crystallite size of 49 nm was obtained after 40 h milling and subsequent annealing at 1000°C for 1 h.

Infrared absorption spectra of calcium phosphate glasses, xCaO·(100-x)P₂O₅ have been investigated by FT-IR spectroscopy. By increasing CaO content, the characteristic bands due to the stretching and bending vibrations were identified and analyzed. The deconvolution of each experimental spectrum was made using a Gaussian-type function. Based on this, the specific structural units of these glasses were identified.

We study the enhancement of the magnetic transition temperature T_c due to incident light in ferromagnetic semiconductors such as EuS. The photoexcited carriers mediate an extra ferromagnetic interaction due to the coupling with the localized magnetic moments increasing the T_c. The Hamiltonian consists of a Heisenberg model for the localized moments and an interaction term between the photoexcited carriers and the localized moments. The model predicts a small enhancement of the transition temperature, about a fraction of a degree K, in semi-quantitative agreement with the experiments.

The damping constant is calculated here at various temperatures for the Raman mode II in s-triazine using the soft mode–hard mode coupling model. The temperature dependence of the order parameter is used as the input data to calculate the damping constant of the Raman mode studied in this coupling model for s-triazine close to the I–II transition (T_c = 198 K). The soft mode–hard mode coupling model which considers the coupling of the soft acoustic mode with the optic modes in s-triazine, is fitted to the observed halfwidths of the Raman mode II close to the I–II phase transition in this crystal.

A hot spot model, involving interaction of pulse laser with nanoparticles where heat diffusion and exothermic chemical reaction are considered and spread out of heat and chemical reaction, is developed to model the thermal reaction dynamic process of Al/NC (nitrocellulose) nanothermites excited by pulse laser for the purpose of verifying the experimental ablation criterion proposed recently and providing a microscopic insight into different physical pathways leading to ablation. In this model, the spatial position and conversion of matters taking place in chemical reactions are regarded as the functions of time, space, and temperature. An exact expression of power density absorbed by nanoparticles in matrix is incorporated to calculate the diameters of chemical reaction region. Calculation results justify experimental ablation criterion, and show that thermal decomposition mechanism predominates the nanosecond pulse-excited process before ablation but it is not suitable for the 100 ps regime which is qualitatively attributed to shock pressure. The effects of pulse duration and nanoparticle size on ablation threshold are examined.

Classical feedback method is used to control chaos in the Liu dynamical system. Based on the Routh–Hurwitz criteria, the conditions of the asymptotic stability of the steady states of the controlled Liu system are discussed, and they are also proved theoretically. Numerical simulations show that the method can suppress chaos to both unstable equilibrium points and unstable periodic orbits (limit cycles) successfully.