17 Results Found

In this work, we investigate the transition from regular dynamics to chaotic behavior in a one-dimensional quartic anharmonic classical oscillator driven by a time-dependent external square-wave force. Owing to energy conservation, the motion of an u...

Electronic, vibrational, and anharmonic studies on some binary clathrate A_xSi₁₃₆ (A = Na, K, Rb, Cs; 0 < x ≤ 24) are theoretically presented. The Fermi energy lies in the range of 1.1 eV to 1.4 eV for Na_xSi₁₃₆ and increases as stoichiometry (x)...

We propose nonlinear model T-symmetry operators having quartic, sextic, octic anharmonicity and inverse quadratics under real spectra. In fact, the model operator is non-Hermitian but real in nature. A comparison with the corresponding hermitian coun...

Comets are likely to contain various carbon oxide molecules potentially including C(O)OC and c-C${}_2$O${}_2$ on their surfaces and comae, as well as their silicon-substituted analogues possibly playing a role in the formation of interstellar dust grains. In t...

Among the few exactly solvable problems in theoretical physics, the 2D (two-dimensional) Newtonian free fall problem in Euclidean space is perhaps the least known as compared to the harmonic oscillator or the Kepler–Coulomb problems. The aim of...

In this paper, we calculated the electronic and optical properties of the harmonic oscillator and single and double anharmonic oscillators, including higher-order anharmonic terms such as the quartic and sextic under the non-resonant intense laser fi...

The vibrational density of states (VDOS) of solids in the low-energy regime controls the thermal and transport properties of materials, such as heat capacity, heat conduction, free energy and entropy. In α-Cristobalite, the low-frequency part of vibr...

The binary compound Mg₃Sb₂ (also written as MgMg₂Sb₂) exhibits a much lower lattice thermal conductivity (${\kappa }_L$) than its ternary analog CaMg₂Sb₂, despite its relatively low mass density and simple crystalline structure. Here, we perform a compara...

The frequency shift of the Raman modes in strontium tungstate (SrWO₄) was investigated in the temperature range from 15 to 295 K. The experimental temperature dependence of the shift was analyzed using both the lattice dynamical calculations and the...

Powder X-ray diffraction measurements were carried out on various samples to characterize their thermal expansion over a wide temperature range (93–1373 K). Using an effective interatomic potential model, we present a method to empirically esti...

We apply the so-called variational Gaussian wavepacket approximation (VGA) for conducting both real- and imaginary-time dynamics to calculate thermal correlation functions. By considering strongly anharmonic systems, such as a quartic potential and a...

A Sagnac atom interferometer can be constructed using a Bose–Einstein condensate trapped in a cylindrically symmetric harmonic potential. Using the Bragg interaction with a set of laser beams, the atoms can be launched into circular orbits, with two...

We consider the problem of heat transport by vibrational modes between Langevin thermostats connected by a central device. The latter is anharmonic and can be subject to large temperature difference and thus be out of equilibrium. We develop a classi...

A high-level ab initio characterization and formation of diaminomethane (DAM), the simplest geminal diamine, is presented to support its spectroscopic detection and astrochemical relevance in the interstellar medium. The C_2v DAM conformer is identifi...

This is a numerical investigation of optical and electronic characteristics of GaAs spherical quantum dots based on single and double quartic potentials and presenting a hydrogenic impurity at their center. The radial Schrödinger equation was so...

Structural and vibrational properties of the aluminium-substituted ternary and quaternary clathrates R₈Al₈Si₁₂₈ (R = Cs, Rb), Cs₈Na₁₆Al₂₄Si₁₁₂ are investigated. The equilibrium volume of R₈Si₁₃₆ expands when all Si atoms at the 8a crystallographic si...

Suspended-carbon nanotubes combine small motional mass, high mechanical frequency, strong electrostatic tunability, and appreciable mechanical nonlinearity. These properties make them attractive for quantum nanomechanics, but they also place unusuall...