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Properties of nonadiabatic quantum fluctuations of the strongly coupled electron-phonon systems

Science china(physics,Mechanics & Astronomy) 2008年第3期51卷 258-268页

作者： PANG XiaoFeng Institute of Life Science and Technology,University of Electronic Science and Technology of china,Chengdu 610054,china international centre for materials physics,chinese academy of sciences,shenyang 110015,china Institute of Life Science Technology University of Electronic Science Technology of china Chengdu 610054 China international centre for materials physics Chinese Academy of Sciences Shenyang 110015 China

A new variational-ansatz of states of electrons and phonons was proposed on the basis of the Holstein model in strongly coupled electron-phonon systems for studying the influence of nonadiabatic phonon fluctuation,arising from the motion and density fluctuation of electrons,on the properties of ground state,uncertainty relation,stability of polarons,charge density wave (CDW) and phonon staggered ordering. The new ansatz represents the correlation among the displacement and squeezing states of phonons and polaron’s state of electrons as well as the squeezing-antisqueezing effect. The correlation and squeezing-antisqueezing ef-fect result in the decrease of ground state energy,enhancement of stability of the systems,increase of binding energy of the polarons,weakening of the growing speed of polaron narrowing of the electron band,increase of the charge density wave order and suppression of the increased tendency of anomalous quantum fluctuation of the phonons in such a case,when compared with the uncorrelated case in the systems. The results obtained show that the ground state determined by the new state ansatz is most stable,thus the new ansatz describing the properties of the coupled electron phonon systems is very relevant and available,especially in strongly coupled and largely squeezed cases.

关键词： squeezing-antisqueezing effect state-ansatz polaron coupled electron-phonon systems quantum fluctuation

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Energy Spectrum of YAG:Cr3+ and Thermal Shifts of Its R Lines

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Communications in Theoretical physics 2005年第7期44卷 165-170页

作者： MA Dong--Ping CHEN Ju--Rong Department of Applied physics, Sichuan University, Chengdu 610065, china international centre for materials physics, the chinese academy of sciences, shenyang 110015, china Department of Applied physics Sichuan University international centre for materials physics the Chinese Academy of Sciences

Traditional ligand-field theory has to be improved bv taking into account both "pure electronic" contributionand electron-phonon interaction one （including lattice-vitbrational relaxation energv）. By means of improved ligand-fieldtheory, R1, R2, R3′, R2′, and R1′ lines, U band, ground-state zero-field-splitting （GSZFS） and ground-state g factors aswell as thermal shifts of R1line and R2line of YAG:Cr3+have been calculated. The results are in very good agreementwith the experimental data. In contrast with ruby, the octahedron of ligand oxygen ions surrounding the central Cr3+ion in YAG:Cr3+is compressed along the [111] direction. Thus, for YAG:Cr3+and ruby, the splitting of t23 4A2(or t23 2E)has opposite order, and the trigonal-field parameters of the two crystals have opposite signs. In thermal shifts of R1andR2lines of YAG:Cr3+, the tetnperature-dependent contributions due to EPI are dominant.

关键词： improved ligand-field theory electron-phonon interaction Stokes shift energy spectrum thermal shift g factor

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Electronic Structure of the Clusters Containing Oxygen in Ni

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Journal of materials Science & Technology 1996年第6期12卷 427-433页

作者： Tao YU Chongyu WANG and Bing WANG (Central Iron and Steel Research Institute, Beijing 100081, china)(To whom correspondence should be addressed)( The international centre for materials physics of the chinese academy of sciences, shenyang 110015, china) Central Iron and Steel Research Institute Beijing 100081 China international centre for materials physics Chinese Academy of Sciences Shenyang 110015 China

The electronic structure of the clusters containing oxygen, the stacking fault and the complex in the transition metal Ni are calculated by the multiple-scattering Xa method. Energy levels,density of states and transfer of charge are obtained. Based on the calculation and analysis,the influences of impurity oxygen and structure defect on the electronic structure of the clusters are discussed, and it is found that the local Ni-o cluster with the interstitial oxygen is a stable atomic configuration.

关键词： Rev Electronic Structure of the Clusters Containing Oxygen in Ni Wang

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Investigation of changes in properties of water under the action of a magnetic field

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Science china(physics,Mechanics & Astronomy) 2008年第11期51卷 1621-1632页

作者： PANG XiaoFeng1,2 & DENG Bo1 1 Institute of Life Science and Technology, University of Electronic Science and Technology of china, Chengdu 610054, china 2 international centre for materials physics, chinese academy of sciences, shenyang 110015, china 1. Institute of Life Science and Technology University of Electronic Science and Technology of China Chengdu 610054 China 2. international centre for materials physics Chinese Academy of Sciences Shenyang 110015 China

The properties of water and their changes under the action of a magnetic field were gathered by the spectrum techniques of infrared, Raman, visible, ultraviolet and X-ray lights, which may give an insight into molecular and atomic structures of water. It was found that some properties of water were changed, and a lot of new and strange phenomena were discovered after magnetization. Magnetized water really has magnetism, which has been verified by a peak shift of X-ray diffraction of magnetized water + Fe3O4 hybrid relative to that of pure water + Fe3O4 hybrid, that is a saturation and memory effect. The properties of infrared and ultraviolet absorptions, Raman scattering and X-ray diffraction of magnetized water were greatly changed relative to those of pure water; their strengths of peaks were all increased, the frequencies of some peaks did also shift, and some new peaks, for example, at 5198, 8050 and 9340 cm?1, occurred at 25°C after water was magnetized. In the meanwhile, the magnetized effects of water are related to the magnetized time, the intensity of an externally applied magnetic field, and the temperature of water, but they are not a linear relationship. The study also showed a lot of new and unusual properties of magnetized water, for example, the six peaks in 3000–3800 cm?1 in infrared absorption, the exponential increase of ultraviolet absorption of wave with the decreasing wavelength of light of 200–300 nm, the frequency-shifts of peaks, a strange irreversible effect in the increasing and decreasing processes, as well as a stronger peak of absorption occurring at 50°C, 70°C and 80°C, the existence of many models of motion from 85°C to 95°C in 8000–10000 cm?1, and so on. These results show that the molecular structure of water is very complicated, which needs further study. Furthermore, the macroscopic feature of mechanics, for instance, surface tension force of magnetized water, was also measured. Experiments discovered that the size in contact angle

关键词： pure water magnetized water magnetic-field physical property spectrum saturation and memory effect mechanical feature surface tension force polarization angles of contact

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A NEW MECHANISM OF ULTRASOUND ATTENUATION IN SINTERED METAL POWDERS

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Acta Metallurgica Sinica(English Letters) 1996年第5期9卷 338-342页

作者： Z. C. Shen( international centre for materials physics, chinese academy of sciences, shenyang 110015, china Suzhou Professional University, Suzhou 215002, china)

This paper analyzes the anomalous power-law dependence of the ultrasound attenuation on frequency by means of a percolation model. It was suggested that the anomaLous ultrasound attenuation is associated with strongly localized eigen modes (to be called fracton) in disordered systems. There exits a steplike increase in the density of vibrational states at crossover frequency ω(co).Computer simulation of vibration spectrum in disordered system is also reported. The density of vibrational states is consistent with the results of relevant experiment outlined above.

关键词： sintered metal powder percolating network fracton ultrasound Attenuation

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电磁场曝露对生物组织电磁特性的影响

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生物化学与生物物理进展 2011年第7期38卷 604-610页

作者：李滚庞小峰电子科技大学生命科学与技术学院生物物理与生物电子学实验室成都610054 中国科学院国际材料物理中心沈阳110015

电磁辐射严重影响着人体的健康.电磁场生物效应的发生机制与电磁场本身的特性相关,同时也与生物组织在电磁场作用下电磁特性的改变密切相关.生物体内的信号分子、自由基以及磁颗粒等处于外加电磁场中时其电磁特性会发生变化,尤其是不同... 详细信息

电磁辐射严重影响着人体的健康.电磁场生物效应的发生机制与电磁场本身的特性相关,同时也与生物组织在电磁场作用下电磁特性的改变密切相关.生物体内的信号分子、自由基以及磁颗粒等处于外加电磁场中时其电磁特性会发生变化,尤其是不同频率电磁场曝露作用下生物组织的导电、介电以及磁学等特性会有非常显著的区别.明确不同频率电磁场作用下生物组织电磁特性的变化规律是研究电磁场生物效应发生机制以及预防问题的关键.综述了近年来电磁场对于生物组织电磁特性影响的研究成果,并对未来的研究方向做了展望.

关键词：电磁辐射生物效应生物组织电磁特性

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Role of Edge and Screw Dislocations in Deformation of Metals

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Journal of materials Science & Technology 1995年第2期11卷 133-136页

作者： Chiwei LUNG(international centre for materials physics, Institute of Metal Research,chinese academy of sciences, shenyang, 110015, china) Inst of Metal Research Shenyang China

It was widely accepted that the screw dislocation is responsible for the strong temperature dependence of the yield stresses observed in bcc metals. In this paper, we show the role of edge dislocations in the deformation of metals and point out that in some cases, its main contribution to the plastic flow behaviour cannot be ignored.

关键词： Crystal structure

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Unusual Behaviour of Dislocation Velocity Exponent in Dislocation Multiplication Model

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Journal of materials Science & Technology 1998年第3期14卷 215-218页

作者： Xaowei WANG(international centre for materials physics, Institute of Metal Research, chinese academy of sciences,shenyang 110015, china) international centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

The chaotic behaviour of dislocation multiplication process was investigated. The change of Lyapunov exponent which is used to determine the stability of quasi-periodic and chaotic behavior as well as that of equilibrium points, and periodic solution was reported by using an iteration model of dislocation multiplication. An unusual behavior of Lyapunov exponent and Feigenbaum exponent which respond to the geometric convergence of orbit from bifurcation to chaos was shown by dislocation velocity exponent m and there is a distinction on the tendency of convergence for the dislocation multiplication model when it was compared with logistic map. It is reasonable for the difference to be analyzed from the materials viewpoint. (Edited author abstract) 9 Refs.

关键词： Unusual Behaviour of Dislocation Velocity Exponent in Dislocation Multiplication Model

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Multirange Fractals in materials: Applications to Fracture and Mechanical Alloying under Ball Milling

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Journal of materials Science & Technology 1997年第4期13卷 255-259页

作者： Chiwei LUNG(international centre for materials physics, Institute of Metal Research,chinese academy of sciences, shenyang 110015, china) international centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

A new model of multirange fractals is proposed to explain the experimental results observed on the fractal dimensions of the fractured surfaces in materials. A new explanation to the Williford's multifractal curve on the relationship of fractal dimension with fracture properties in materials has been given. It shows the importance of fractorizing out the effect of fractal structure from other physical causes and separating the appropriate range of scale from multirange fractals. Mechanical alloying process under ball milling as a non-equilibrium dynamical system has been also analyzed.

关键词： Ball Applications to Fracture and Mechanical Alloying under Ball Milling Multirange Fractals in materials

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Universality and Specificity of Fractal Dimension of Fractured Surfaces in materials

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Journal of materials Science & Technology 2000年第1期16卷 1-4页

作者： Chiwei LUNG and Shenggang WANG (international centre for materials physics, Institute of Metal Research, chinese academy of sciences, shenyang 110015, china) international centre for materials physics Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China

After calculation on the fracture angles under various conditions of specific surface energies with different symmetry operations of rotation, the complicated behavior of dependence of fractal dimension on the structure of crystal is shown. It is found that the crack propagates along the weakest crystal plane no matter what the direction of the maximum stress is if the anisotropy is sufficiently strong; and then, the fractal dimension of the fractured surfaces might be determined by the approximate fractal structure already existed in the material. Specificity of the fractal dimension of fractured surfaces would be easy to appear in this case. Reversely, the crack propagates along the direction of the maximum stress no matter what direction of the weakest crystal plane is if the anisotropy is sufficiently weak. Universality of the fractal dimension of fractured surfaces would be possible to appear in this case. In many real materials, universality and specificity of the materials are associated. The fractal dimension measured may more or less be influenced by the structure of materials and it shows its universality through the specificity of materials.

关键词： Universality and Specificity of Fractal Dimension of Fractured Surfaces in materials

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