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Accurate prediction of interference minima in linear molecular harmonic spectra by a modified two-center model

Chinese physics B 2016年第3期25卷 163-168页

作者：崔鑫张頔玉陈高陈基根曾思良郭福明杨玉军 Institute of Atomic and Molecular Physics Jilin UniversityChangchun 130012China Jilin Provincial Key Laboratory of Applied Atomic and Molecular Spectroscopy Jilin UniversityChangchun 130012China School of Science Changchun University of Science and TechnologyChangchun 130022China Department of Physics and Materials Engineering Taizhou UniversityTaizhou 318000China Institute of Applied Physics and Computational Mathematics Beijing 100088China

We demonstrate that the interference minima in the linear molecular harmonic spectra can be accurately predicted by a modified two-center model. Based on systematically investigating the interference minima in the linear molecular harmonic spectra by the strong-field approximation （SFA）, it is found that the locations of the harmonic minima are related not only to the nuclear distance between the two main atoms contributing to the harmonic generation, but also to the symmetry of the molecular orbital. Therefore, we modify the initial phase difference between the double wave sources in the two-center model, and predict the harmonic minimum positions consistent with those simulated by SFA.

关键词： high-order harmonic generation molecular harmonics

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Investigation on the influence of atomic potentials on the above threshold ionization

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Chinese physics B 2014年第5期23卷 238-243页

作者：田原野李苏宇魏珊珊郭福明曾思良陈基根杨玉军 Institute of Atomic and Molecular Physics Jilin University Data Center for High Energy Density Physics Institute of Applied Physics and Computational Mathematics Science and Technology Computation Physics Laboratory Institute of Applied Physics and Computational Mathematics Department of Physics and Materials Engineering Taizhou University

We systematically investigate the influence of atomic potentials on the above-threshold ionization （ATI） spectra in one-dimensional （1D） cases and compare them with the three-dimensional （3D） case by numerically solving the time-dependent Schrrdinger equation. It is found that the direct ionization plateau and the rescattering plateau of the ATI spectrum in the 3D case can be well reproduced by the 1D ATI spectra calculated from the supersolid-core potential and the soft-core potential, respectively. By analyzing the factors that affect the yield of the ATI spectrum, we propose a modified-potential with which we can reproduce the overall 3D ATI spectrum. In addition, the influence of the incident laser intensities and frequencies on the ATI spectra calculated from the proposed modified potential is studied.

关键词： above threshold ionization model potential angular distribution of photoelectron

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ADAPTIVE ITERATION ACCELERATION FOR NONLINEAR PARABOLIC-HYPERBOLIC SYSTEM

ADAPTIVE ITERATION ACCELERATION FOR NONLINEAR PARABOLIC-HYPE...

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第二届热问题计算方法国际会议

作者： Xia Cui,Guang-Wei Yuan,jing-Yan Yue National Key Laboratory of Science and Technology on computational physics, institute of applied physics and computational mathematics,Beijing 100088,China

A new iteration scheme named adaptive Picard-Newton iteration is studied for a nonlinear coupled parabolic-hyperbolic *** can accelerate the resolving procedure with flexible adjustment of the adaptive *** includes Picard iteration and Picard-Newton iteration as special cases. Theoretical analysis shows its solution has super-linear convergence rate to the solution of the nonlinear discrete scheme of the original problem,and second order spatial and temporal approximations to the real solution of the *** tests verify its high accuracy and *** factors are picked up by comparisons of several iterations,and significant synthesis acceleration is gained.

关键词： Coupled Parabolic-Hyperbolic System Nonlinearity Adaptive Iteration Acceleration

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Prandtl number effects in MRT lattice Boltzmann models for shocked and unshocked compressible fluids

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Theoretical & applied Mechanics Letters 2011年第5期1卷 60-63页

作者： Feng chen,1 Aiguo Xu,2,Guangcai Zhang,2 and Yingjun Li 1,1) State Key Laboratory for GeoMechanics and Deep Underground Engineering,China University of Mining and Technology (Beijing),Beijing 100083,China 2) National Key Laboratory of computational physics,institute of applied physics and computational mathematics,P.O.Box 8009-26,Beijing 100088,China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing 100088 China

This paper constructs a new multiple relaxation time lattice Boltzmann model which is not only for the shocked compressible fluids,but also for the unshocked compressible *** make the model work for unshocked compressible fluids,a key step is to modify the collision operators of energy flux so that the viscous coefficient in momentum equation is consistent with that in energy equation even in the unshocked *** unnecessity of the modification for systems under strong shock is *** model is validated by some well-known benchmark tests,including thermal Couette flow,Riemann *** first system is unshocked and the latter is *** both systems,the Prandtl number effects are *** agreements are obtained between new model results and analytical ones.

关键词： lattice Boltzmann method compressible flows multiple-relaxation-time Prandtl number

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Lie symmetries and conserved quantities of nonholonomic electromechanical systems

Lie symmetries and conserved quantities of nonholonomic elec...

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2011 World Congress on Engineering and Technology(CET 2011)

作者： Gang-Ling Zhao 1,2 1 Shanghai institute of applied mathematics and Mechanics Shanghai University,Shanghai, China 2 Department of physics and Information Engineering Shangqiu Normal University, Shangqiu, China Li-Qun chen Department of Mechanics Shanghai University,Shanghai,China jing-Li Fu institute of Mathematical physics, Zhejiang Sci-Tech University, Hangzhou, China

This paper focuses on studying Lie symmetries and conserved quantities of nonholonomic electromechanical system. Based on the infinitesimal transformation, we establish the Lie symmetric determining equations and restrictive equations and the definition of Lie symmetries before the structure equations and conserved quantities of the Lie symmetries are obtained. Finally, an example is presented for illustrating the results.

关键词： Lie symmetry conserved quantity infinitesimal transformation nonholonomi celectromechanical system

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反射镜双程放大对类氖锗软X射线激光的输出影响研究

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物理学报 2011年第10期60卷 307-313页

作者：安红海王琛方智恒熊俊孙今人王伟傅思祖乔秀梅郑无敌张国平上海激光等离子体研究所上海201800 北京应用物理与计算数学研究所北京100080

纳秒量级激光驱动的类氖锗软X射线激光具有出光稳定和输出强度大等优点,在诸多领域拥有很好的应用价值.研究了通过在光路中增加一块多层膜反射镜实现双程放大对出光特性的影响.通过估算和实验,证实了增加反射镜双程放大确实能够提高类... 详细信息

纳秒量级激光驱动的类氖锗软X射线激光具有出光稳定和输出强度大等优点,在诸多领域拥有很好的应用价值.研究了通过在光路中增加一块多层膜反射镜实现双程放大对出光特性的影响.通过估算和实验,证实了增加反射镜双程放大确实能够提高类氖锗软X射线激光的输出强度,对于24mm的双程放大长度,总输出强度会增加约2.3倍.但同时这种模式也带来了光束质量的下降,对应用研究并非完全有益.

关键词：软X射线激光反射镜双程放大增益饱和

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A systematic investigation of high harmonic generation using mid-infrared driving laser pulses

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Science China(physics,Mechanics & Astronomy) 2010年第6期53卷 1054-1059页

作者： YAO JinPing 1,2 ,XIONG Hui 1 ,XU Han 1 ,FU YuXi 1,2 ,ZENG Bin 1,2 ,CHU Wei 1,2 ,chenG Ya 1 ,XU ZhiZhan 1 ,LIU XiaoJun 3 & chen jing 4,5 1 State Key Laboratory of High Field Laser physics,Shanghai institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,China 3 State Key Laboratory of Magnetic Resonance and Atomic and Molecular physics,Wuhan institute of physics and mathematics,Chinese Academy of Sciences,Wuhan 430071,China 4 institute of applied physics and computational mathematics,Beijing 100088,China 5 Center for applied physics and Technology,Peking University,Beijing 100084,China 1. State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China4. Institute of Applied Physics and Computational Mathematics Beijing 100088 China5. Center for Applied Physics and Technology Peking University Beijing 100084 China

We report on a systematic investigation of the influences of gas pressure,focal position and focusing geometry on high harmonic generation by use of mid-infrared femtosecond laser pulses. We also discuss the spatial characteristics of harmonics under different focusing conditions. By optimizing the parameters,we experimentally observed the generation of 1 kHz,low divergence coherent X-ray beams in the water-window region.

关键词： mid-infrared laser pulses high harmonic generation water window

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Ab initio study of a Y-doped Σ31 grain boundary in alumina

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Science China(physics,Mechanics & Astronomy) 2008年第11期51卷 1607-1615页

作者： chen Jun, XU Yun, chen DongQuan & ZHANG jingLin Laboratory of computational physics, institute of applied physics and computational mathematics, Beijing 100088, China 1. Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

The atomic structures and energetics of clean and Y-doped general grain boundary (GB) Σ31/(0001) models in α-Al2O3 are studied by a series of high precision ab initio calculations. A large supercell with 700 atoms and periodic boundary conditions is adopted for undoped and Y-doped GB with different substitution sites and con-centrations. It is shown that Y atoms preferably segregate to the central column of the 7-member Al ring. This is explained as more favorable bond formation for Y in this position and lower GB energy. The calculated GB formation energy for the clean and Y-doped cases is respectively 3.99 and 3.67 J/m2. On the average, the GB region in Σ31 has a slightly lower charge density than the bulk crystalline region. In addtition, the GB induces a long ranged asymmetric electrostatic potential distri-bution on each side of the grain boundary.

关键词： alumina grain boundary Y-doped ab initio

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Parallel FDTD Analysis of Large-Scale Ridged TEM Horn Antenna Array

Parallel FDTD Analysis of Large-Scale Ridged TEM Horn Antenn...

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2009 International Conference on Microwave Technology and computational Electromagnetics(ICMTCE 2009)

作者： Chang Lei 1 ,Liao cheng 1 ,Zhou Hai-jing 2 ,Li Hai-Yu 2 ,chen Ling-Lu 1 ,and Fu Hai-Jun 1 1 institute of Electromagnetics,Southwest Jiaotong University,chengdu 610031,China 2 institute of applied physics and computational mathematics,Beijing 100088,China

Parallel computation is an effective way to solve large-scale electromagnetic problems which can provide enough computer memory and reduce the computing time. In this paper the program of the parallel Finite Difference Time Domain (FDTD) based on the JASMIN framework is proposed. The parallel FDTD program was used for simulating the electric dipole source and a ridged TEM horn antenna. The obtained parallel efficiency was as high as 80% even when 128 computers were employed. Numerical results show that the program is correct and efficient. A large-scale array of ridged TEM horn antenna was simulated. Its near-field and far-field results were given. The example provides a solution for studying large-scale antenna array and shows that the program has the ability to solve large-scale electromagnetic problems.

关键词： FDTD,Parallel,JASMIN framework,Ridged TEM horn antenna array.

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Positron-impact excitation of hydrogen atoms in Debye plasmas

Positron-impact excitation of hydrogen atoms in Debye plasma...

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第十五届全国原子与分子物理学术会议

作者： S.B.Zhang~1,X.J.chen~1 and J.G.Wang~2 1 Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern physics,University of Science and Technology of China,Hefei 230026,China 2 The Key Laboratory of computational physics,institute of applied physics and computational mathematics,P. O.Box 8009,Beijing 100088,China

The positron-impact excitation of hydrogen atoms embedded in plasma environments is investigated using the close-coupling approximation in the low to intermediate-energy region,and the excitation cross sections for 1s→2s,1s→2p and 2s→2p processes have been calculated in a wide Debye parameter *** screening interactions, described by the Debye-H(?)ckel model,decrease the coupling matrix elements,resulting in the reduction of the excitation cross sections from a few percent to one magnitude of *** will alter remarkably the spectroscopy of hydrogen in intensity and position,which should be considered in the simulation and diagnostics in some specific plasma conditions.

关键词： positron-impact excitation Debye plasmas close-coupling approximation

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