Calculation of the Critical Distances in a System of Two Colliding Nuclei Beyond the Monopole Approximation

A method for calculating electronic levels in compact superheavy nuclear quasimolecules based on solving the Dirac equation in spherical coordinates using a multipole expansion of a two-center potential is developed. It is shown that, for internuclear distances up to ∼100 fm, such a technique enables fast convergence, which allows one to calculate the electronic energy levels with an accuracy better than 10−6. Moreover, all the multipole moments can be calculated analytically. The critical distances between the similar colliding nuclei have been calculated in the range Z ∼ 87–100 for bottom electronic levels: even 1σg and odd 1σu, respectively.     

Entanglement Evolution of a Two-Qubit System beyond Rotating-Wave Approximation

Two noninteracting qubits, initially entangled in Bell states, are coupled to a one-mode cavity and evolve under its influence. The entanglement evolution of the two qubits is investigated beyond the rotating-wave approximation. It is shown that the counter-rotating wave terms have a great influence on the disentanglement behavior.     

Calculation of Nuclear Stopping in the Semiclassical Approximation

Technical Physics - The results of calculating nuclear stopping in the semiclassical approximation for the H–Be, H–C, H–W, O–C, O–Be, and O–Al systems are...     

A Study of Giant Monopole an. d. Quadrupole States in the Relativistic Thomas-Fermi Approximation

The isoscalar giant monopole and quadrupole states in finite nuclei are studied in a relativistic δ-ω model by making use of a local Lorentz boost and scaling method, and the nuclear surface and the density distribution are treated in the relativistic Thomas-Fekmi approximation.The excitation energies of the giant resonances are self-consistently calculated. It is found that the excitation energies of giant monopole arehbasically in agreement with experimental data for all nuclei and those of giant quadrupole for light nuclei. Coupling constants and δ-meson mass in the theory are chosen to fit static properties of nuclear matter.     

Calculation of the Dynamic Stark Effect in the Many-Level Approximation

A new method for calculating the dynamic Stark effect in a circular polarized electric field of arbitrary strength and frequency is proposed. The basic equations of the method are given. By way of illustration the results of calculation of the shift and splitting of energy levels of a He atom in a circular polarized electric field are considered.     

Calculation of optical properties within the Local Density Approximation to Density Functional Theory: application to palladium

We calculate the optical functions of Pd using the ab initio, all-electron Full Potential Linear Muffin Tin Orbital method within the framework of the Density Functional Theory in the Local Density approximation. We test, in the case of Pd, the convergence of the dielectric function and energy loss function in different energy ranges vs. the completeness of the basis and give a quantitative estimate of the accuracy. The present approach opens the possibility of extending the energy range where the optical functions can be calculated with good accuracy without increasing the computational effort. Received 4 September 2001     

An Approximation for the Density Matrix in Calculations of the Mean-Field Potential of the Interaction of Nuclei

An approximation has been proposed for the nucleus single-particle density matrix in calculating the exchange component of the mean-field potential in the double-folding model. The method is based on the pseudo-oscillator representation of the density matrix and makes it possible to separate single-particle and internucleon variables, which greatly simplifies and accelerates the process of calculating the mean-field potential. Test calculations based on examples of alpha-particle interactions with ¹²C, ¹⁶O, and ⁴⁰Ca nuclei have shown the adequacy of the proposed approximation.     

基于理想流体对称碰撞模型的爆炸焊接流场角变形计算

 采用理想流体对称碰撞模型,分析了爆炸焊接流场中沿流线的物理变形,推导出了角变形的理论计算公式,并采用Visual C++语言对其进行了编程计算,获得了驻点近区角变形的大小及变化规律。结果表明,在驻点近区,沿来流至出流方向角变形逐步增大,其变化率在驻点附近最大;沿出流方向,给定碰撞角,角变形随来流速度的增加而增大;给定来流速度,角变形随碰撞角的增大而减小。从理论和实验方面,间接地将计算结果与前人的结论进行了对比验证,结果是一致的,以此为基础配合驻点近区的应变率场,讨论了其对爆炸焊接波状界面形成的影响。     

Quantum Corrections to the Entropy of a Black Hole with a Global Monopole

Quantum corrections to the entropy of a static, spherically symmetric blackhole—global monopole system arising from the Dirac spinor field are investigatedby using the brick wall method. It is shown that if we ignore the usual contributionfrom the vacuum surrounding the system, then the quantum corrections for thestatic black hole consist of two parts: One is a quadratically divergent term whichtakes a geometric character. The other is a logarithmically divergent term whichis not proportional to the area of the horizon. The renormalization of the quadraticand logarithmic divergences is also investigated.     

High Phonon Frequency Approximation in the Calculation of Phonon Drag Magnetothermopower

At high magnetic fields and low temperatures the phonon drag magnetothermopower is dominated by phonons with energies much greater than k_BT. This fact is used to develop an approximate formula which can be evaluated in a few percent of the time required by the rigorous result. We show that the predominant contribution to the magnetothermopower comes from the transition process in which both the initial Landau level and the final Landau level have the same quantum number n = n'= n_f where nf distinguishes the level nearest to the Fermi energy. A double summation over n and n'can therefore be neglected. In the temperature range of 1.275 K to 5.005 K, all the HPFA results agree with the experimental data and the rigorous theoretical results qualitatively. At T = 2.495 and 2.937 K, the HPFA results arein fair quantitative accordance with the experimental data and the rigorous theoretical results.     

A Clifford Algebra Approach to the Classical Problem of a Charge in a Magnetic Monopole Field

The motion of an electric charge in the field of a magnetic monopole is described by means of a Lagrangian model written in terms of the Clifford algebra of the physical space. The equations of motion are written in terms of a radial equation (involving r=|r|, where r(t) is the charge trajectory) and a rotor equation (written in terms of an unitary operator spinor R). The solution corresponding to the charge trajectory in the field of a magnetic monopole is given in parametric form. The model can be generalized in order to describe the motion of a charge in the field of a magnetic monopole and other additional central forces, and as an example, we discuss the classical ones involving linear and inverse square interactions.