Low energy orbital magnetic dipole excitations of heavy nonspherical nuclei

To clarify the physical nature of the orbital magnetic dipole excitations discussed widely in the past few years, a semiclassical model is presented and the nuclei¹⁵⁶Gd and¹⁶⁴Dy are investigated microscopically. The semi-classical model involves a consistent treatment of vibrational and rotational degrees of freedom; the microscopic results are obtained in quasiparticle-random-phase approximation (QRPA) with a realistic effective interaction. The results disagree with the picture of scissors modes or rotational vibrations.Dedicated to Prof. Dr. H.J. Mang on the occasion of his 60th birthday     

Kinetic theory of rotating molecule interaction with a solid surface

A kinetic theory of interaction between molecules with rotational degrees of freedom and a solid surface for arbitrary ratios among the times of molecule rotation, flight through the region of surface forces, and relaxation of a molecular ensemble due to phonons has been developed. A kinetic equation for an ensemble of molecules residing in the field of surface forces has been derived from the equation for the one-particle distribution function of molecules by averaging it along the dynamical trajectories in the region of surface force action. A simple analytic expression for the probability of trapping a molecule with rotational degrees of freedom has been obtained. Experimental data on rotational cooling and rotational polarization of desorbed molecules are discussed. Zh. éksp. Teor. Fiz. 113, 1350–1363 (April 1998)     

Increasing thermoelectric efficiency: a dynamical systems approach

Inspired by the kinetic theory of ergodic gases and chaotic billiards, we propose a simple microscopic mechanism for the increase of thermoelectric efficiency. We consider the cross transport of particles and energy in open classical ergodic billiards. We show that, in the linear response regime, where we find exact expressions for all transport coefficients, the thermoelectric efficiency of ideal ergodic gases can approach the Carnot efficiency for sufficiently complex charge carrier molecules. Our results are clearly demonstrated with a simple numerical simulation of a Lorentz gas of particles with internal rotational degrees of freedom.     

Rigid rotators and diatomic molecules via Tsallis statistics

We obtain an analytic expression for the specific heat of a system of N rigid rotators exactly in the high temperature limit, and via a perturbative approach in the low temperature limit. We then evaluate the specific heat of a diatomic gas with both translational and rotational degrees of freedom, and conclude that there is a mixing between the translational and rotational degrees of freedom in nonextensive statistics.     

Five- and eight-vector extensions of relativistic quantum theory: The preferred reference frame

The complex quaternion approach to relativistic quantum theory is extended to include time, in the preferred cosmic reference frame, as a fifth dimension. Particle mass appears as an eigenvalue of this invariant operator. Closing the extended algebra also suggests three additional space-time components, possibly related to microscopic rotational degrees of freedom and the scale setting fundamental length. The Dirac, Klein-Gordon, Maxwell, and Einstein equations are generalized to accommodate 5- and 8-vector space-time, including gravitational curvature. The usual conserved probability density is shown to harbor fundamental difficulties.     

One-Dimensional Hamiltonian for Columnar Liquid Crystals

A one-dimensional Hamiltonian is derived upon microscopic considerations to model the columnar phases of a liquid crystal made of molecules of discrete rotational symmetry. The study deals with the ground state of this Hamiltonian, only the orientational degrees of freedom being taken into account. The intracolumnar interaction is described by the natural cantedness of an isolated column, while interaction parameters H and G characterize the amplitude of the local crystal field at a site originating from the other surrounding columns. The phase diagrams of the orientational ordering along the column are numerically investigated and a previous analytical approach is briefly recalled. A new perturbation development is proposed. This allows us to analyse a multiphase point and to explain the appearance of an infinity of phases in the vicinity of this point. The anisotropy of the columnar lattice is then investigated with the use of the same perturbation development, and some of the properties of a complex phase diagram are examined numerically as well as analytically.     

Translational-rotational interaction in dynamics and thermodynamics of a two-dimensional atomic crystal with molecular impurities

The interaction between the rotational degrees of freedom of a diatomic impurity molecule and phonon excitations of a two-dimensional atomic matrix commensurate to the substrate is investigated theoretically. It is shown that the translational-rotational interaction leads to renormalization of the crystal field constants and a change in the form of the operator for the rotational kinetic energy as compared to the corresponding expression for a free rotator. The contribution from the rotational degrees of freedom of impurities to the low-temperature heat capacity of a diluted solution of diatomic molecules in the two-dimensional atomic matrix is calculated. The possibility of experimentally observing the predicted effects is discussed.     

Relation Between the Gap at Z=64 Subshell and the Abrupt Transition in the Region N=88～90

The onset of deformation in the N=88～90 region and the effects of the gap at Z=64 subshell on nucler structure are investigated in a microscopic approach of the interacting boson model.It turns out that,besides the n-p interaction,the distribution of single particle levels in the shell model space also plays a direct and important role in the rapid transition of spectrum structure.For Nd～Dy nuclei the calculations show excellent agreement agreement with experimental energy systematics.     

Semi-classical model of neutron rearrangement using quantum coupled-channel approach

A quantum coupled-channel approach with collective degrees of freedom (the rotation of deformed nuclei and/or their surface vibrations) is combined with an empirical coupled-channel model to add neutron rearrangement channels to vibrational and rotational excitations. The calculated fusion cross sections and the barrier distribution functions for several combinations of nuclei are in good agreement with experimental data.     

三轴形变对102Rh旋称反转的影响

将两准粒子加轴对称转子模型扩展到三轴形变, 对奇奇核102Rh的旋称反转进行了研究和分析, 结果表明, 可能的旋称反转机制 (即低K 空间n p相互作用和科氏力的相互竞争), 对于A=100质量区奇奇核也是适用的, 三轴形变可以明显地改进能谱的振荡特性. The model of an axially symmetric rotor plus two quasi particles for the Signature Inversion (SI) in odd odd nuclei is generalized to the triaxial deformation. The calculation of the odd odd nucleus 102Rh shows that the possible SI mechanism (i. e., the competition between the n p interaction and the coriolis force in low K space) is also appropriate for odd odd nuclei in the A=100 region. A triaxial shape can improve the vibration property of the rotational spectra remarkably.     

Construction of the mass velocity profile for a rarefied molecular gas entrained by a rotating sphere taking into account thermophysical parameters of the gas

The problem of a sphere rotating in a molecular gas is solved in the isothermal approximation. The expression for the velocity of a rarefied molecular gas entrained by a sphere rotating in it is derived for sliding flow conditions taking into account the second-order correction in the Knudsen number. A generalization of the Boltzmann kinetic equation in the BGK model to the case of rotational degrees of freedom of gas molecules is used as the basic equation. The diffusive reflection model is employed as the microscopic boundary condition on the surface of the sphere. It is shown that this approach makes it possible to take into account the dependence of the gas velocity on the Prandtl number and gas temperature.     

Tetrads and q-Theory

JETP Letters - As the microscopic structure of the deep relativistic quantum vacuum is unknown, a phenomenological approach (q-theory) has been proposed to describe the vacuum degrees of freedom...     

Rarefied molecular gas flow near the rotating cylindrical surface

An exact analytic solution of the problem of the right circular cylinder in a rarefied molecular gas is constructed in the isothermal approximation. An expression for the velocity of a rarefied molecular gas entrained by the cylinder rotated therein is obtained in the regime of a flow with slip accounting for the second-order correction in terms of the Knudsen number. A generalization of the BGK model of the Boltzmann kinetic equation accounting for the rotational degrees of freedom of gas molecules is used as the governing equation, and the diffuse reflection model is used as a microscopic boundary condition on the cylinder surface. The given approach is shown to enable the consideration of the gas flow dependence on the Prandtl number and the gas temperature.     

Neutron-proton interaction and nuclear deformations

In Hartree-Fock-Bogoliubov calculations with and without the neutron-proton (n-p) interaction for a few nuclei in the s-d shell and in the rare-earth region it is found that the n-p interaction is the major source of nuclear deformation.     

Effective theory for deformed nuclei

Techniques from effective field theory are applied to nuclear rotation. This approach exploits the spontaneous breaking of rotational symmetry and the separation of scale between low-energy Nambu–Goldstone rotational modes and high-energy vibrational and nucleonic degrees of freedom. A power counting is established and the Hamiltonian is constructed at next-to-leading order.     

Reorientations and random fields in plastic crystals

A simple Ising-like model is presented to describe the phase diagram of plastic crystals. In addition to a bilinear coupling between translations and rotations a reorientation-translation coupling is introduced via random fields which couple solely to rotational degrees of freedom. The physical basis of the reorientation-translation coupling is discussed using the rotational state hypothesis. The present approach is found to be consistent with some recent neutron experiments.     

Photon Green’s functions for a consistent theory of absorption and emission in nanostructure-based solar cell devices

The light-matter interaction in planar nanostructures with applications in photovoltaic devices is investigated by means of a microscopic quantum-kinetic theory based on the non-equilibrium Green’s function formalism. The Dyson and Keldysh equations for the Green’s functions of photons are solved numerically. The result is used to couple the optical and electronic degrees of freedom via respective self-energies. The numerical approach for the solution of the optical problem is verified against a standard transfer-matrix formalism and applied to the computation of absorption and emission characteristics in ultra-thin-absorber solar cells.     

Multidimensional Langevin approach to description of near-barrier heavy-ion fusion and deep-inelastic collisions

A six-dimensional Langevin approach is developed for the analysis of near-barrier heavy-ion fusion and deep-inelastic collisions. In its framework, vibrational and rotational degrees of freedom of both nuclei are taken into account explicitly. Calculated fusion cross sections, compound nuclei spin distributions, and angular and energy distributions of deep-inelastic products show satisfactory agreement with experimental data.