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Superconductivity of small metal grains

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Science china(physics,Mechanics & Astronomy) 2005年第4期48卷 431-441页

作者： ZHENG Renrong1 CHEN Zhiqian2 & ZHU Shunquan1,3 1. department of physics, Shanghai Normal university, Shanghai 200234, china 2. department of physics, Southwest Normal university, Chongqing 400715, china 3. department of Computer and Electric Technology, Shanghai Business School, Shanghai 201400, china 1. department of physics Shanghai Normal University 200234 Shanghai China 2. department of physics Southwest Normal University 400715 Chongqing China 3. department of Computer and Electric Technology Shanghai Business School 201400 Shanghai China

The formulas of the energy gap and superconducting critical temperature appropriate for systems with both odd and even number of electrons are derived; the bases of the derivations are BCS theory and energy level statistics. Numerical results qualitatively agree with the experimental phenomena. i.e., the superconductivity of small metallic grains will first enhance then decrease to zero when the grain are getting smaller and smaller. The calculations indicate that the above phenomena happen in the metallic grains belonging to Gaussian Orthogonal Ensemble (GOE) and Gaussian Unitary ensemble (GUE) with zero spin; The superconductivity of small metallic grains in Gaussian Symplectic Ensemble (GSE) will monotonically decrease to zero with the decreasing of the grain size. The analyses suggest that the superconductivity enhancements come from pairing and the balance of the strengths between spin-orbital coupling and external magnetic field. In order to take the latter into account, it is necessary to include the level statistics given by Random Matrix Theory (RMT) in describing small metallic grains.

关键词： size effect, superconductivity enhancements, small metallic grains.

Effect of Substrate-Water Interaction on the Wetting Behavior in Water-Oil and Substrate-Water-Oil Systems

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Wuhan university Journal of Natural Sciences 2003年第4A期8卷 1097-1102页

作者： Yuan Yin-quan 1,2 , Zou Xian-wu 1 , Jin Zhun-zhi 1 1. School of physics and Technology, Wuhan university, Wuhan 430072, Hubei, china 2. department of physics, Xiaogan university, Xiaogan 432100, Hubei, china Wuhan university School of Physics and Technology Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***) Xiaogan university Department of Physics Xiaogan Hubei China (GRID:grid.49470.3e) Wuhan university School of Physics and Technology Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

The effects of the substrate-water interaction on the wetting behavior in water-oil and surfactant-water-oil systems confined by one substrate which has the preferential interaction to one species of particles have been investigated by using the free energy analysis and discontinuous molecular dynamic simulations. As the preferential interaction between the substrate and water particles varies from small repulsion to large attraction, the partial drying, partial wetting and complete wetting state are observed in sequence. In addition, the wetting behavior of surfactant aqueous solution on the substrate is not only dependent on the interaction, but also limited by the maximum equilibrium concentration of surfactants at the interface.

关键词： wetting behavior wetting transition preferential interaction substrate

Stochastic bi-resonance induced by external noise for Ca^2+ signaling in hepatocytes

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Science china Chemistry 2005年第4期48卷 286-291页

作者： ZHANG Jiqian1,2,HOU Zhonghuai1 & XIN Houwen1 1.department of Chemical physics,university of Science and Technology of china,Hefei 230026,china 2.College of physics and Electronic Information,Anhui Normal university,Wuhu 241000,china 1. department of Chemical physics University of Science and Technology of China 230026 Hefei China 2. College of physics and Electronic Information Anhui Normal University 241000 Wuhu China

The influence of external noise on intracellular Ca2+ oscillations dynamics in a single cell of rat hepatocytes is *** coherence of noise-induced intracellular Ca2+ oscillations reached two maxima for multiple external noise intensity,indicating the occurrence of external noise stochastic bi-resonance (SBR).This phenomenon is compared with our previous result that was induced by internal ***,the deterministic bifurcation character of the system was also discussed.

关键词： stochastic bi-resonance, environment fluctuation, calcium oscillations.

Virtualities of quark and gluon in QCD vacuum

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Science china(physics,Mechanics & Astronomy) 2008年第10期51卷 1439-1447页

作者： ZHOU LiJuan1, QIN SongMei2, WU Qing3 & MA WeiXing4 1 Collaboration Group of Hadron physics and Non-perturbative QCD Study, Guangxi university of Tech- nology, Liuzhou 545006, china 2.department of physics, Guangxi university, Nanning 540003, china 3 department of physics, Qingdao university, Qingdao 266071, china 4 Institute of High Energy physics, Chinese Academy of Sciences, Beijing 100049, china 1. Collaboration Group of Hadron physics and Non-perturbative QCD Study Guangxi University of Technology Liuzhou 545006 China 2. department of physics Guangxi University Nanning 540003 China 3. department of physics Qingdao University Qingdao 266071 China 4. Institute of High Energy physics Chinese Academy of Sciences Beijing 100049 China

The non-local vacuum condensates of quantum chromodynamics (QCD) describe the distributions of quarks and gluons in the non-perturbative QCD vacuum state. Physically, this means that vacuum quarks and gluons have a nonzero mean-squared momentum in the vacuum, called virtuality. The quark virtuality is given by the ratio of the local quark-gluon mixed vacuum condensate to the quark local vacuum condensate. The gluon virtuality is expressed by gluon vacuum condensates and four-quark vacuum condensates. We study the two virtualities by solving Dyson-Schwinger Equations and calculating quark and gluon vacuum condensates. Our theoretical results for quark virtuality are in good agreement with many other theoretical model predictions such as QCD sum rules and lattice QCD calculations. Our calculation on gluon virtuality is initial and the results are quite interesting.

关键词： quark gluon virtuality QCD vacuum condensate non-perturbative QCD

BINDING　ENERGY　OF　THE　SHALLOW　DONOR　IN　（CdTe）_m／（ZnTe）_n　STRAINED　DOUBLE　QUANTUM　WELL

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Acta Metallurgica Sinica(English Letters) 1996年第2期9卷 103-108页

作者： XING Jinhai(department of physics,Liaoning university,Shenyang 110036,china)HUANG Heluan(department of Electronic Science and Engineering,Liaoning university,110036,china) Liaoning Univ Shenyang China

In this paper the binding energy of the *** in CdTe/ZnTe strained double quantum well was *** effect of the finite well potential and strain,resulting from the lattice mismatch,on the binding energy of the impurity is included in a variational *** binding energy is obtained as a function of the well width,barrier width,and impurity position in the barrier by using a variational *** result of the present calculation shows that the variational law of the binding energy is similar to that of unstrained materials.

关键词： binding energy shallow donor strained double quantum well CdTe ZnTe

Electronic structure and magnetism of R(Fe,Si)_(12) (R=Y,Nd)

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Science china(physics,Mechanics & Astronomy) 2006年第2期49卷 195-202页

作者： SUN Guang’ai1, CHEN Bo1, DU Honglin2, FAN Zhijian1, GAO Tao3 & QI Xinhua31. Institute of Nuclear physics and Chemistry, china Academy of Engineering physics, Mianyang 621900, china 2. department of physics, Peking university, Beijing 100871, china 3. Institute of Atomic and Molecular physics, Sichuan university, Chengdu 610065, china 1. Institute of Nuclear physics and Chemistry China Academy of Engineering Physics Mianyang 621900 China 2. department of physics Peking university Beijing 100871 China 3. Institute of Atomic and Molecular physics Sichuan University Chengdu 610065 China

The newly developed full-potential linearized augmented plane wave (LAPW) and local orbitals (lo) based on standard APW methods are briefly introduced, and the structure and magnetic properties of R(Fe, Si)12 compounds (R = Y, Nd) are calculated using the method. The distribution of Si at different sites is analyzed based on total energy of one crystal unit with structure having been optimized. The characters of magnetic mo-ments, total density of states (TDOS) and partial density of states (PDOS) for different crystal sites Si occupies are obtained and analyzed. The results show that the total mag-netic moments of RFe10Si2 (R = Y, Nd) are larger than those of RFe10M2 (M = Ti, V, Cr, Mn, Mo and W) and the hybridization mechanism is seen as follows. Si(8j) reduce the mag-netic moments of Fe at three sites, however, Si(8f) mainly reduce the magnetic moments of Fe(8i) and Fe(8j) atoms. The Curie temperature is markedly enhanced by the introduc-tion of Si atoms according to spin fluctuation of DOS at Fermi level.

关键词： (L)APW+lo method R(Fe Si)12(R = Y Nd) magnetic moment Density of state.

Constructing super Gabor frames:the rational time-frequency lattice case

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Science china Mathematics 2010年第12期53卷 3179-3186页

作者： LI ZhongYan 1 & HAN DeGuang 2, 1 department of Mathematics and physics, North china Electric Power university, Beijing 102206, china 2.department of Mathematics, university of Central Florida, Orlando, FL 32816, USA 1. department of Mathematics and physics North China Electric Power University Beijing 102206 China2. Department of Mathematics University of Central Florida Orlando FL 32816 USA

For a time-frequency lattice Λ = A Z d × B Z d , it is known that an orthonormal super Gabor frame of length L exists with respect to this lattice if and only if |det( AB) | = 1 L . The proof of this result involves various techniques from multi-lattice tiling and operator algebra theory, and it is far from constructive. In this paper we present a very general scheme for constructing super Gabor frames for the rational lattice case. Our method is based on partitioning an arbitrary fundamental domain of the lattice in the frequency domain such that each subset in the partition tiles R d by the lattice in the time domain. This approach not only provides us a simple algorithm of constructing various kinds of orthonormal super Gabor frames with flexible length and multiplicity, but also allows us to construct super Gabor (non-Riesz) frames with high order smoothness and regularity. Several examples are also presented.

关键词： super Gabor frame orthonormal super frame full rank lattice tiles

Hawking radiation and thermodynamics of a Vaidya-Bonner black hole

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Research in Astronomy and Astrophysics 2010年第1期10卷 33-38页

作者： Zhen-Feng Niu Wen-Biao Liu department of physics Hebei North University Zhangjiakou 075000 China department of physics Institute of Theoretical Physics Beijing Normal University Beijing 100875 China

Using Parikh＇s tunneling method, the Hawking radiation on the apparent horizon of a Vaidya-Bonner black hole is calculated. When the back-reaction of particles is neglected, the thermal spectrum can be precisely obtained. Then, the black hole thermodynamics can be calculated successfully on the apparent horizon. When a relativistic perturbation is applied to the apparent horizon, a similar calculation can also lead to a purely thermal spectrum. The first law of thermodynamics can also be derived successfully at the new supersurface near the apparent horizon. When the event horizon is thought of as a deviation from the apparent horizon, the expressions of the characteristic position and temperature are consistent with the previous viewpoint which asserts that the thermodynamics should be based on the event horizon. It is concluded that the thermodynamics should be constructed exactly on the apparent horizon while the event horizon thermodynamics is just one of the perturbations near the apparent horizon.

关键词： black hole physics -- relativity -- kinematics and dynamics

Spontaneous chiral-symmetry breaking of lattice QCD with massless dynamical quarks

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Science china(physics,Mechanics & Astronomy) 2007年第1期50卷 6-14页

作者： LUO XiangQian department of physics,School of physics and Engineering,Sun Yat-Sen university,Guangzhou 510275,china 1. department of physics School of Physics and Engineering Sun Yat-Sen University Guangzhou 510275 China

One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods of the lattice gauge theory, one has to perform expensive simulations at multiple bare quark masses, and employ some modeled functions to extrapolate the data to the chiral limit. This paper applies the probability distribution function method to computing the chiral condensate in lattice QCD with massless dynamical quarks, without any ambiguous mass extrapolation. The results for staggered quarks indicate that this might be a promising and efficient method for investigating the spontaneous chiral-symmetry breaking in lattice QCD, which deserves further investigation.

关键词： lattice QCD spontaneous chiral-symmetry breaking dynamical quarks