首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
We analyze the dynamics of a bright soliton in atomic scattering length in an expulsive parabolic potential. Bose-Einstein condensates (BECs) with time-dependent Under a safe ravage of parameters in which the Gross-Pitaevskii (GP) equation is effective in one dimension, our results show that, the dynamics of the bright soliton can be classed into two phases, depending on the value of the scattering length. Meanwhile, there exists a critical value of the absolute value of the atomic scattering length, below which, the dynamics of the bright soliton is very regular. Those phenomena can be useful for developing concrete applications of the nonlinear matter waves. We also obtain the orbital equation of the bright soliton and get some interesting data which may be useful for the experimental observation of the bright soliton and the application of the atom laser with manipulated intensity.  相似文献   

2.
葛自明  吕志伟  王治文  周雅君 《物理学报》2002,51(12):2733-2739
使用全实加关联(fullcorepluscorrelation缩写为FCPC)和里兹(Ritz)变分方法计算了类锂体系(Z=11—20)激发态1s2nd(n=3,4,5)的非相对论能量和波函数;包括动能修正、电子电子接触项、轨道轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出,量子电动力学(quantumelectronicdynamics缩写为QED)修正由有效核电荷方法和类氢公式计算;给出了高电离类锂体系激发态的激发能、精细结构和项能(termenergy),并 关键词: 类锂体系 全实加关联 精细结构 激发能  相似文献   

3.
Molybdenum is nitrided by a 100-Hz pulsed DC glow discharge technique for various time durations and fill gas pressures to study the effects on the surface properties of molybdenum. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) are used for the structural and morphological analysis of the nitrided layers. Vickers' microhardness tester is utilized to investigate surface microhardness. Phase analysis shows the formation of more molybdenum nitride molecules for longer nitriding durations at fill gas pressures of 2 mbar and 3 mbar (1 bar = 105 Pa). A considerable increase in surface microhardness (approximately by a factor of 2) is observed for longer duration (10 h) and 2-mbar pressure. Longer duration (10 h) and 2-mbar fill gas pressure favors the formation of homogeneous, smooth, hard layers by the incorporation of more nitrogen.  相似文献   

4.
The nonrelativistic energies for lithium isoelectronic sequence 1s2ng and 1s2nh (n=5, 6, 7, and 8) states from Z=3 to 8 are calculated by using a full core plus correlation (FCPC) method with multiconfiguration interaction wave functions. Relativistic and mass-polarization effects on the energy are evaluated as the first-order perturbation theory. Our predicted excitation energies are compared with previous experimental results in the literature.  相似文献   

5.
Electron mobility scattering mechanism in AlN/GaN heterostuctures is investigated by temperature-dependent Hall measurement, and it is found that longitudinal optical phonon scattering dominates electron mobility near room temperature while the interface roughness scattering becomes the dominant carrier scattering mechanism at low temperatures (~ 100 K). Based on measured current-voltage characteristics of prepared rectangular AlN/GaN heterostructure field-effect transistor under different temperatures, the temperature-dependent variation of electron mobility under different gate biases is inves- tigated. The polarization Coulomb field (PCF) scattering is found to become an important carrier scattering mechanism after device processing under different temperatures. Moreover, it is found that the PCF scattering is not generated from the thermal stresses, but from the piezoelectric contribution induced by the electrical field in the thin A1N barrier layer. This is attributed to the large lattice mismatch between the extreme thinner AlN barrier layer and GaN, giving rise to a stronger converse piezoelectric effect.  相似文献   

6.
This paper reports that an experimental investigation of fast pitch angle scattering (FPAS) of runaway electrons in the EAST tokamak has been performed. From the newly developed infrared detector (HgCdTe) diagnostic system, the infrared synchrotron radiation emitted by relativistic electrons can be obtained as a function of time. The FPAS is analysed by means of the infrared detector diagnostic system and the other correlative diagnostic systems (including electron-cyclotron emission, hard x-ray, neutrons). It is found that the intensity of infrared synchrotron radiation and the electron-cyclotron emission signal increase rapidly at the time of FPAS because of the fast increase of pitch angle and the perpendicular velocity of the energetic runaway electrons. The Parail and Pogutse instability is a possible mechanism for the FPAS.  相似文献   

7.
陈超  王治文 《中国物理》2003,12(6):604-609
The electron density at the nucleus, ρ(0), and the radial expectation values, (-2≤n≤10), of the ground state for the lithium isoelectronic sequence are calculated with a full core plus correlation (FCPC) wavefunctions. By using these obtained expectation values, the accurate inequalities of the electron density at the nucleus and the radial expectation values derived by Gálvez and Porras for these systems are examined and verified. The final results show that FCPC wavefunctions used in this work can give satisfactory results in full configuration space.  相似文献   

8.
The electron density at the nucleus ρ(0) and radial expectation values 〈rn〉 (n=-2–10) of the ground state for lithium-like systems from Z=11 to 18 are calculated with the full core plus correlation wave functions. By using these obtained expectation values, accurate inequalities of radial expectation values derived by Gálvez and Porras [Phys. Rev. A 44, 144 (1991)] are examined and verified. The final results show that the full core plus correlation wave functions for lithium-like systems with higher nuclear charge are also accurate in the full configuration space and can give satisfactory electron density at the nucleus and radial expectation values.  相似文献   

9.
We report on measurements of the cross section and provide first data on spin correlation parameters A(TT') and A(TL') in inclusive scattering of longitudinally polarized electrons from nuclear-polarized hydrogen. Polarized electrons were injected into an electron storage ring operated at a beam energy of 720 MeV. Polarized hydrogen was produced by an atomic beam source and injected into an open-ended cylindrical cell, located in the electron storage ring. The four-momentum transfer squared ranged from Q2 = 0.2 GeV(2)/c(2) at the elastic scattering peak to Q2 = 0.11 GeV(2)/c(2) at the Delta(1232) resonance. The data provide a stringent test of pion electroproduction models.  相似文献   

10.
Relativistic mean-field theory and phase-shift analysis are combined together to investigate the elastic Coulomb scattering between electrons and unstable nuclei. Electron scattering at several different energies is studied and compared, in order to see the energy dependence of electron-nucleus scattering. It is shown that electron scattering at 200 MeV or 300 MeV can be used to reveal electron-nucleus scattering information around the first diffraction minimum. Shifts in opposite directions are obtained for the first diffraction minima of the electron scattering off the ground and first excited states of ^17F with ^16O as reference, and similar effects are obtained for ^18Ne. Besides, some neutron-rich N = 8 isotones are also studied. Results show that electron scattering will be very useful and important in studying both proton- and neutron-rich nuclei in the future.  相似文献   

11.
In order to trace azimuthal angle dependence of the initial interaction in ultra-relativistic heavy ion collision, two azimuthal multiplicity-correlation patterns neighboring and fixed-to-arbitrary angularbin correlation patterns -- are suggested. From the simulation of Au + Au collisions at √SNN = 200 GeV by using the Monte Carlo models RQMD with hadron re-scattering and AMPT with and without string melting, we observe that the correlation patterns change gradually from out-of-plane preferential one to inplane preferential one when the centrality of collision shifts from the central collision to peripheral collision, meanwhile the anisotropic collective flow v2 keeps positive in all cases. This regularity is found to be collision energy independent. The physics behind the two opposite trends of correlation patterns, in particular, the presence of out-of-plane correlation patterns at RHIC energy, are discussed.  相似文献   

12.
Up to now the chirality is seldom studied in the diluted spin glass although many investigations have been performed on the site-ordered Edwards-Anderson model. By simulation, we investigate the dynamicaJ properties of both the spin-glass and the chiral-glass phases in a diluted dipolar system, which was manifested to have a spin-glass transition by recent numerical study. By scaling we find that both phases have the same aging behavior and closer aging parameterμ. Similarly, the domains grow in the same way and both phases have a closer barrier exponent g2. It means that both the spins and the chirality have the same dynamical properties and they may freeze at the same temperature.  相似文献   

13.
By making use of the quasi-two-dimensional (quasi-2D) model, the current-voltage (l-V) characteristics of In0AsA10.82N/A1N/GaN heterostructure field-effect transistors (HFETs) with different gate lengths are simulated based on the measured capacitance-voltage (C-V) characteristics and I-V characteristics. By analyzing the variation of the electron mobility for the two-dimensional electron gas (2DEG) with electric field, it is found that the different polarization charge distributions generated by the different channel electric field distributions can result in different polarization Coulomb field scatterings. The difference between the electron mobilities primarily caused by the polarization Coulomb field scatterings can reach up to 1522.9 cm2/V.s for the prepared In0.38AI0.82N/A1N/GaN HFETs. In addition, when the 2DEG sheet density is modulated by the drain-source bias, the electron mobility presents a peak with the variation of the 2DEG sheet density, the gate length is smaller, and the 2DEG sheet density corresponding to the peak point is higher.  相似文献   

14.
B.  Rezaei 《理论物理通讯》2010,(9):518-520
The properties of muonic helium atom (^4He+2μ-e-) in ground state are considered. In this work, the energy and average distance between particles have been obtained using a wave function, which satisfies boundary conditions. It is shown that the obtained energy are very close to the values calculated by others. But the small differences of the expectation values of r^2n are due to the incorporated boundary conditions in proposed wave function and are expected.  相似文献   

15.
The nonrelativistic dipole-length, -velocity and -acceleration absorption oscillator strengths for the 1s22s-1s22p transitions of the lithium isoelectronic sequence from Z=11 to 20 are calculated by using the energies and the multiconfiguration interaction wave functions obtained from a full core plus correlation (FCPC) method. In most cases, the agreement between the oscillator strengths values from the length and velocity formula is up to four or five digit. Our results are also in good agreement with previous theoretical data available in the literature.  相似文献   

16.
The gl(1/1) supersymmetric vertex model with domain wall boundary conditions (DWBC) on an N × N square lattice is considered. We derive the reduction formulae for the one-point boundary correlation functions of the model. The determinant representation for the boundary correlation functions is also obtained.  相似文献   

17.
In complex networks, network modules play a center role, which carry out a key function. In this paper, we introduce the spatial correIation function to describe the relationships among the network modules. Our focus is to investigate how the network modules evolve, and what the evolution properties of the modules are. In order to test the proposed method, as the examples, we use our method to analyze and discuss the ER random network and scale-free network. Rigorous analysis of the existing data shows that the introduced correlation function is suitable for describing the evolution properties of network modules. Remarkably, the numerical simulations indicate that the ER random network and scale-free network have different evolution properties.  相似文献   

18.
In this paper, we present a comprehensive investigation of the effects of the transverse correlation function (TCF) on the thermodynamic properties of Heisenberg antiferromagnetic (AFM) and ferromagnetic (FM) systems with cubic lattices. The TCF of an FM system is positive and increases with temperature, while that of an AFM system is negative and decreases with temperature. The TCF lowers internal energy, entropy and specific heat. It always raises the free energy of an FM system but raises that of an AFM system only above a specific temperature when the spin quantum number is S 〉 1. Comparisons between the effects of the TCFs on the FM and AFM systems are made where possible.  相似文献   

19.
We investigate the single-event two-pion correlation functions for the hydrodynamic particle-emitting sources with the fluctuating initial conditions generated by the Heavy Ion Jet Interaction Generator (HIJING). Using a three-dimension fast Fourier transform (FFT), we further extract the source functions from the single-event correlation functions. It is found that the inhomogeneity of the hydrodynamic sources with the fluctuating initial conditions lead to event-by-event fluctuations of the correlation functions and source functions.  相似文献   

20.
Understanding the cause of the synchronization of population evolution is an important issue for ecological improvement. Here we present a Lotka-Volterra-type model driven by two correlated environmental noises and show, via theoretical analysis and direct simulation, that noise correlation can induce a synchronization of the mutualists. The time series of mutual species exhibit a chaotic-like fluctuation, which is independent of the noise correlation, however, the chaotic fluctuation of mutual species ratio decreases with the noise correlation. A quantitative parameter defined for characterizing chaotic fluctuation provides a good approach to measure when the complete synchronization happens.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号