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First-principles study of the electronic structure and optical properties of cubic Perovskite NaMgF_3

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Chinese physics B 2014年第3期23卷 469-474页

作者：李贞丽安辛友程新路王雪敏张红彭丽萍吴卫东 institute of Atomic and Molecular physics Sichuan University Science and Technology on Plasma physics Laboratory Research Center of Laser Fusion Chinese Academy of Engineering Physics

The structural, electronic, and optical properties of cubic perovskite NaMgF3 are calculated by plane-wave pseudopo- tential density functional theory. The calculated lattice constant a0, bulk modulus B0, and the derivative of bulk modulus B~ are 3.872/~, 78.2 GPa, and 3.97, respectively. The results are in good agreement with the available experimental and theo- retical values. The electronic structure shows that cubic NaMgF3 is an indirect insulator with a wide forbidden band gap of Eg = 5.90 eV. The contribution of the different bands is analyzed by total and partial density of states curves. Population analysis of NaMgF3 indicates that there is strong ionic bonding in the MgF2 unit, and a mixture of ionic and weak covalent bonding in the NaF unit. Calculations of dielectric function, absorption coefficient, refractive index, electronic energy loss spectroscopy, optical reflectivity, and conductivity are also performed in the energy range 0 to 70 eV.

关键词： density functional theory cubic perovskite NaMgF3 electronic properties optical properties

Large Third-Order Optical Nonlinearity of Cadmium Sulphide Nanoparticles Embedded in Polymer Thin Films

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Chinese physics Letters 2009年第9期26卷 267-270页

作者：王存修付世书顾玉宗 institute of Microsystem physics Henan University Kaifeng 475004

A simple method for synthesis of well dispersed cadmium sulphide nanoparticles embedded in a polyethylene glycol matrix （PEG 400） in thin film form is presented. The large blue shift of the band gap energy of the CdS nanoparticles compared to the bulk semiconductors is observed via UV-vis absorption spectra. Photoluminescence spectra of CdS nanocomposite films show that the emission peaks shift towards the longer wavelength with the increase of annealing temperature. Transmission electron microscopic images as well as Raman scattering studies confirm the CdS nanometer size particle formation within the polymer matrix. The particle size is about 8 nm. Selected area electron diffraction （SAED） shows the cubic zinc blende polycrystalline rings. Third-order optical nonlinearity of the CdS nanopartieles embedded in polymer thin films is studied with the Z-scan technique under 1064 nm excitation. The results show that the CdS nanocomposite film exhibits negative nonlinear refraction index and positive absorption coefficient. The film shows large optical nonlinearity, and the magnitude of the third-order nonlinear susceptibility of the film is calculated to be 1.73 × 10^-9 esu. The corresponding mechanism is discussed.

关键词： sea surface nonliear interaction numerical method

Absorption Cross Section of Einstein-Maxwell Dilation Axion Black Hole for Dirac Particles

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Communications in Theoretical physics 2007年第12期48卷 1051-1054页

作者： LIU Chang-Qing JING Ji-Liang institute of physics and Department of physics,Hunan Normal University,Changsha 410081,China institute of physics and Department of physics Hunan Normal University Changsha 410081 China

The absorption cross section of the Einstein-Maxwell Dilaton Axion (EMDA) black hole for Dirac particlesis *** is shown that the absorption cross section decreases as both the v and the absolute value of the dilatonincrease,but it increases as the mass of the particle *** is also shown that the absorption cross section for themassless Dirac particles is 1/8 of the area of the horizon,which may be an universal property for minimally coupledmassless Dirac particles.

关键词： black hole absorption cross section Dirac particle

In-vivo behavior of tin-radiopharmaceuticals

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Nuclear Science and Techniques 2003年第2期14卷 127-130页

作者： HE Jia-Heng, LUO Shun-Zhong, WANG Guan-Quan, YANG Yu-Qing, PU Man-Fei, LIU Guo-Ping (institute of Nuclear physics and Chemistry, the Chinese Academy of Engineering physics, Mianyang 621900) institute of Nuclear physics and Chemistry the Chinese Academy of Engineering Physics Mianyang 621900

Tin is an essential ingredient of most technetium-99m radiopharmaceuticals but its in-vivo distribution and long-term fate are not well understood. This work describes distribution in mice of several tin-117m labeled compounds. The results indicate that stannic-HEDTMP appears to be the best overall bone localizing agent with very low blood, muscle, kidney, or liver uptake, and its binding to bone is higher than that of tin-117m-DTPA, which make it potentially useful as an agent for skeletal scintigraphy and radiotherapy of bone tumors.

关键词：放射性药品锡骨肿瘤闪烁扫描法放射线疗法

A numerical study on Rayleigh-Taylor instability of aluminum plates driven by detonation

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Science China(physics,Mechanics & Astronomy) 2010年第2期53卷 195-198页

作者： HE ChangJiang,ZHOU HaiBing & HANG YiHong institute of Applied physics and Computational Mathematics,Laboratory of Computational physics,Beijing 100088,China institute of Applied physics and Computational Mathematics Laboratory of Computational Physics Beijing China

The authors,using elastic-plastic hydrodynamic code,present the Rayleigh-Taylor (RT) instability of Al plates driven by high-explosive detonation. Our numerical study assumes the material is fluid,or it is an elastic-plastic solid,and we compare the results of these simulations with the experimental data. For the numerical simulation of Rayleigh-Taylor instability of the metal driven by high-explosive detonation,the elastic-plastic effect must be assumed. The result of the simulation is different from the experiment,using only equation of state. However,the growth of perturbation agrees well with the measured growth under the second assumption. There is a cutoff wavelength for RT instability of the metal. The growth of perturbation is stable for short wavelength. The growth increases rapidly as the wavelength increases.

关键词： interface instability elastic-plastic numerical simulation

High winding number of topological phase in non-unitary periodic quantum walk

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Chinese physics B 2021年第10期30卷 120-126页

作者： Yali Jia Zhi-Jian Li institute of Theoretical physics Shanxi UniversityTaiyuan 030006China

Topological phases and their associated multiple edge states are studied by constructing a one-dimensional non-unitary multi-period quantum walk with parity-time *** is shown that large topological numbers can be obtained when choosing an appropriate time *** maximum value of the winding number can reach the number of periods in the one-step evolution *** validity of the bulk-edge correspondence is confirmed,while for an odd-period quantum walk and an even-period quantum walk,they have different configurations of the 0-energy edge state andπ-energy edge *** the boundary,two kinds of edge states always coexist in equal amount for the odd-period quantum walk,however three cases including equal amount,unequal amount or even only one type may occur for the even-period quantum walk.

关键词： periodic quantum walk high winding number edge states

On the Role of Neutral Particles on Edge Turbulence in the CT-6B Tokamak

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Chinese physics Letters 1998年第7期15卷 510-512页

作者： WANG Gui-ding YANG Xuan-zong FENG Chun-hua JIANG Di-ming QI Xia-zhi institute of physics Chinese Academy of SciencesBeijing 100080

A positive limiter biasing on the CT-6B tokamak resulted in a slight increase of edge density and an obvious drop of electron temperature,which is in the temperature range where the rate coefficients for ionization processes are strongly temperature ***,edge fluctuations are enhanced,suggesting that the presence of neutral particles may play an important role in modifying edge turbulence.

关键词： tokamak turbulence Tokamak

Kinetics of Spherical Interface in Crystal Growth

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Chinese physics Letters 2017年第4期34卷 112-115页

作者： Mei-Qin Fu Qing-Ling Bi Yong-Jun Lu School of physics Beijing Institute of Technology Beijing 100081

The growth kinetics of spherical NiAl and CuZr crystals are studied by using molecular dynamics simulations. The growth rates of crystals are found to increase with the grain radius. The simulations show that the interface thickness and the Jackson α-faetor increase as the growth proceeds, indicating that the interface becomes increasingly rough during growth. Due to the increasing interface roughening, the fraction of repeatable growth sites at interface f is proposed to actually increase in growth. An attachment rate, which is defined as the fraction of atoms that join the crystal interface without leaving, is used to approximate f, displaying a linear increase. With this approximation, we predict the growth rates as a function of the crystal radius, and the results qualitatively agree with those from the direct simulations.

关键词： Kinetics of Spherical Interface in Crystal Growth

Collision dynamics of He@C_(60)+He@C_(60) at low energies

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Science China(physics,Mechanics & Astronomy) 2008年第7期51卷 765-772页

作者： ZHAO Qiang1,2, ZHANG FengShou1,2,3 & ZHOU HongYu1,2 1 Key Laboratory of Beam Technology and Material Modification of Ministry of Education, institute of Low Energy Nuclear physics, Beijing Normal University, Beijing 100875, China 2 Beijing Radiation Center, Beijing 100875, China 3 Center of Theoretical Nuclear physics, National Laboratory of heavy Ion Accelerator of Lanzhou, Lanzhou 730000, China Key Laboratory of Beam Technology and Material Modification of Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing China Beijing Radiation Center Beijing China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Accelerator of Lanzhou Lanzhou China

A semi-empirical molecular dynamics model is developed. The central collisions of C60+C60 and He@C60+He@C60 at different incident energies are investigated based on this model. It is found that the dimer structures have been produced at proper incident energies and these fullerene dimers could be formed by a self-assembly of C60 fullerene and He@C60. The He atom has a significant effect at higher incident energy and this embedded He atom can enhance the stability of the dimer structure.

关键词： C60 He@C60 collision molecular dynamics