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Theoretical Analysis of Generalized Oscillator Strengths for Helium by R-Matrix Method

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Chinese Physics Letters 2004年第1期21卷 54-56页

作者：韩小英李家明 centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084

The high-energy electronic-impact excitation cross section is directly proportional to the generalized oscillator strength (GOS) of the target atom. The generalized oscillator strengths of helium atom from the ground state to the excited states (21S, 21P and 31D) are calculated using the updated R-matrix codes within the first Born approximation. Our calculation results are in good agreement with the previous theoretical and experimental results at high incident energies. In order to treat the bound-bound and bound-continuum transitions in a unified manner, the GOS density is defined based on the quantum defect theory. We calculate the GOS densities of 1S, 1P and 1D channels, namely the complete high-energy collision cross sections of electronic-impact excitations into all the n1S, n1P and n1D excited states. In addition to high-energy excitation cross sections, a scheme to calculate the excitation cross sections for entire incident energy range is discussed.

关键词： Atomic and molecular physics

Determination of the Geometric Structure of Core Excited Silane Based on Photoabsorption Spectra Near the Si 2p Edges

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Chinese Physics Letters 2002年第8期19卷 1085-1087页

作者：许如清李家明等 DepartmentofPhysics CenterforAtomicandMolecularNanosciencesTsinghuaUniversityBeijing100084

The photoabsorption spectra near the Si 2p edges of SiH4 have been studied based on the multiple-scattering self-consistent-field method. Our theoretical calculations provide clear assignments of the inner-shell photoabsorption spectra. In comparison with high-resolution experimental spectra, the geometric structure of the Si 2p excited SiH4 * * is recommended as C2v symmetry

关键词： photoabsorption Spectra Caste determination silanes MULTIPLE SCATTERING Sex Determination Processes core NATIONAL EMERGENCY ALARM REPEATER geometrical construction

Structure Stability of I—Type Carbon Nanotube Junctions

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Chinese Physics Letters 2002年第10期19卷 1487-1489页

作者：夏丹李家明等 centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084 InstituteofPhysics ChineseAcademyofSciencesBeijing100080

Carbon nanotubes with junctions may play an important role in future `nanoelectronics' and future `nano devices'. In particular, junctions constructed with metal and semiconducting nanotubes have potential applications. Based on the orthogonal tight-binding molecular dynamics method, we present our study of the structure stability of I-type carbon nanotube junctions.

关键词： Junction Device Component Structural stability Carbon Nanotubes Metals Nanodevice Nanoelectronics

Theoretic Study of C Ⅱ Recombination Line

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Chinese Physics Letters 2004年第9期21卷 1723-1726页

作者：彭永伦王民盛韩小英李家明 centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084 DepartmentofPhysics ShanghaiJiaotongUniversityShanghai200080

Using the R-matrix method, we carry out theoretical calculations for recombination line λ 8794Å(3d'-3p') of CII, which is important to estimate the abundances of carbon in planetary nebulae. Our calculations are based on three sets of target orbital basis, through which we elucidate the electron correlation and static polarization effects in the dielectronic recombination processes.

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A Remote Quantum Adding Machine

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Chinese Physics Letters 2002年第11期19卷 1579-1580页

作者：张圣醒龙桂鲁等 DepartmentofPhysics TsinghuaUniversityBeijing100084 KeyLaboratoryforQuantumInformationandMeasurements MinistryofEducationBeijing100084 centerforatomicandmolecularnanosciences T

We design a scheme to perform additions of N remote addends. This adder is useful for some quantum information processing purposes, such as statistics and multi-party quantum game. The quantum remote adder is construc... 详细信息

关键词： Adders

Oscillator Strengths for 2s~2-2p~2P Transitions of the Lithium IsoelectronicSequence from NaIX to CaXVIII

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Communications in Theoretical Physics 2005年第2期43卷 305-308页

作者： CHENChao WANGZhi-Wen centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084China DepartmentofPhysics LiaoningNormalUniversityDalian116029China

The nonrelativistic dipole-length, -velocity and -acceleration absorptionoscillator strengths for the 1s~22s-1s~22p transitions of the lithium isoelectronic sequence from Z= 11 to 20 are calculated by using the energies and the multiconfiguration interaction wavefunctions obtained from a full core plus correlation (FCPC) method. In most cases, the agreementbetween the oscillator strengths values from the length and velocity formula is up to four or fivedigit. Our results are aiso in good agreement with previous theoretical data available in theliterature.

关键词： oscillator strengths lithium isoelectronic sequence full core pluscorrelation method

Energies of 1s~2ng and 1s~2nh (n = 5, 6, 7, and 8) States for LithiumIsoelectronic Sequence

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Communications in Theoretical Physics 2005年第5期43卷 886-890页

作者： CHENChao WANGZhi-Wen PhysicsDepartment LiaoningNormalUniversityDalian116029China centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084China

The nonrelativistic energies for lithium isoelectronic sequence 1s~2ng and1s~2nh (n = 5,6,7, and 8) states from Z = 3 to 8 are calculated by using a full core pluscorrelation (FCPC) method with multiconGguration interaction wave functions. Relativistic andmass-polarization effects on the energy are evaluated as the first-order perturbation theory. Ourpredicted excitation energies are compared with previous experimental results in the literature.

关键词： lithium-like system full-core plus correlation excitation energy

Can a Single－Wall Carbon Nanotube be an X－Ray Waveguide？

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Chinese Physics Letters 2004年第3期21卷 447-449页

作者：孙煜杰程曜王锋李家明 DepartmentofEngineeringPhysics TsinghuaUniversityBeijing100084 centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084 InstituteofPhysics ChineseAcademyofSciencesBeijing100080

We study the transport efficiency for x-rays of single-wall carbon nanotubes (SWCNTs) in theory. Three effects, i.e. refraction, absorption and x-ray tunnelling loss, are considered. Our calculation shows that the SWCNT cannot be an x-ray waveguide due to the large x-ray tunnelling loss. If the tunnelling loss can be reduced effectively, a nanotube could be a waveguide.

关键词： Instrumentation and measurement Surfaces interfaces and thin films Nanoscale science and low-D systems

Quantum Propagator for Arbitrary Potentials on General Grids

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Chinese Physics Letters 2004年第4期21卷 644-647页

作者：林尚何春龙李家明 DepartmentofPhysics ShanghaiJiaotongUniversityShanghai200030 centerforatomicandmolecularnanosciences DepartmentofPhysicsTsinghuaUniversityBeijing100084 InstituteofPhysics ChineseAcademyofSciencesBeijing100080

The point-to-point Feynman quantum propagator has an analytic form only for quadratic potentials. We apply the split operator approach to obtain a propagator matrix for arbitrary potentials for non-uniform grids, which are particularly useful for real physical potentials with both rapid-varying and smooth regions. We exemplify our method with the wavefunction propagation and the extraction of an eigenvalue and an eigenfunction of a Morse system modelling diatomic molecules.

关键词： Atomic and molecular physics Computational physics