共查询到20条相似文献,搜索用时 93 毫秒
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电介质的极化机制与介电常量的分析 总被引:6,自引:1,他引:5
在简介电介质极化机制的基础上,通过Lorentz振子模型及其修正,分析电介南的极化机制与介电常量,比较分析了一些电介质介常量有规律的变化,分析了一些电介质介电常量与光频介电常量相等的微观机制。 相似文献
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普朗克常量h是能量量子化概念的基石, 更是理解量子力学诸多内容的关键, 本文从4个方面介绍了普
朗克常量的意义和应用, 包括其在量子力学两种形式中的基础作用、 对量子化概念发展的帮助、 改变对物质世界连
续性认识的启发以及质量新标准建立中的作用 相似文献
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将分子动力学方法与基于第一性原理的COMPASS势相结合在0K到1300K范围内将Ni放在NPT和NPH系综中进行模拟,计算了弹性常量、压缩比、线性扩张常量等物理量。计算结果与实验数据良好相符,通过计算表明采取合理的方法和计算参数,Ni的热力学性质可以比较准确地计算出来,这可为实验和理论上进一步的研究提供有意义的参考。 相似文献
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Gravitational instabilities of isothermal spheres are studied in the presence of a positive or negative cosmological constant, in the Newtonian limit. In gravity, the statistical ensembles are not equivalent. We perform the analysis both in the microcanonical and the canonical ensembles, for which the corresponding instabilities are known as ‘gravothermal catastrophe’ and ‘isothermal collapse’, respectively. In the microcanonical ensemble, no equilibria can be found for radii larger than a critical value, which is increasing with increasing cosmological constant. In contrast, in the canonical ensemble, no equilibria can be found for radii smaller than a critical value, which is decreasing with increasing cosmological constant. For a positive cosmological constant, characteristic reentrant behavior is observed. 相似文献
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For the 1D fully asymmetric exclusion model with open boundary conditions, we calculate exactly the fluctuations of the current of particles. The method used is an extension of a matrix technique developed recently to describe the equatime steady-state properties for open boundary conditions and the diffusion constant for particles on a ring. We show how the fluctuations of the current are related to non-equal-time correlations. In the thermodynamic limit, our results agree with recent results of Ferrari and Fontes obtained by working directly in the infinite system. We also show that the fluctuations of the current become singular when the system undergoes a phase transition with discontinuities along the first-order transition line. 相似文献
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A precise knowledge of the Newtonian gravitational constant G has an important role in physics and is of considerable meteorological interest. Although G was the first physical constant to be introduced and measured in the history of science, it is still the least precisely
determined of all the fundamental constants of nature. The 2002 CODATA recommended value for G, G = (6.6742 ± 0.0010) × 10−11m3 · kg−1 · s−2, has an uncertainty of 150 parts per million (ppm), much larger than that of all other fundamental constants. Reviewed here
is the status of our knowledge of the absolute value of G, methods for determining G, and recent high precision experiments for determining G. 相似文献
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The momentum distribution and dynamical structure factor in a weakly interacting Bose gas with a time-dependent periodic modulation in terms of the Bogoliubov treatment are investigated. The evolution equation related to the Bogoliubov weights happens to be a solvable Mathieu equation when the coupling strength is periodically modulated. An exact relation between the time derivatives of momentum distribution and dynamical structure factor is derived, which indicates that the single-particle property is strongly related to the two-body property in the evolutions of Bose-Einstein condensates. It is found that the momentum distribution and dynamical structure factor cannot display periodical behavior. For stable dynamics, some particular peaks in the curves of momentum distribution and dynamical structure factor appear synchronously, which is consistent with the derivative relation. 相似文献
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