Browsing by Author "Lin, CD"

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Charge transfer in slow collisions of H+ with Na
(2003-07-01)
Le, AT
;
Liu, CN
;
Lin, CD
;
物理研究所
;
Institute of Physics
We reexamined charge-transfer cross sections for protons colliding with Na(3s) atoms for collision energies from the threshold at 1.7 eV to 40 eV using the recently developed hyperspherical close-coupling method. Our results disagree with the recent calculations by Dutta [Phys. Rev. A 63, 022709 (2001)], but are in good agreement with the earlier calculations of Croft and Dickinson [J. Phys. B 29, 57 (1996)] except at energies below 3 eV. Our calculations support the doubt on the experimental data of Kushawaha.
Comprehensive convergence study of TCAO close-coupling method for the excitation and ionization in keV H+-H collisions
(1996-11-28)
Kuang, JY
;
Lin, CD
;
物理研究所
;
Institute of Physics
Convergence of the two-centre atomic orbital (TCAO) close-coupling calculations for the excitation and ionization of atomic hydrogen by keV proton impact is carefully examined using various large basis sets on each centre; It is shown that reliable cross sections for the weak channels can only be obtained with a large number of basis states on the target and a limited number of bound states on the projectile. Cross sections for excitation to 2l, 3l, 4l and 5l states and for ionization are presented and compared to available experimental data and to other theoretical calculations.
Comprehensive convergence study of TCAO close-coupling method for the excitation and ionization in keV H+-H collisions
(1996-11-28)
Kuang, JY
;
Lin, CD
;
物理研究所
;
Institute of Physics
Convergence of the two-centre atomic orbital (TCAO) close-coupling calculations for the excitation and ionization of atomic hydrogen by keV proton impact is carefully examined using various large basis sets on each centre; It is shown that reliable cross sections for the weak channels can only be obtained with a large number of basis states on the target and a limited number of bound states on the projectile. Cross sections for excitation to 2l, 3l, 4l and 5l states and for ionization are presented and compared to available experimental data and to other theoretical calculations.
Convergent TCAO close-coupling calculations for electron transfer, excitation and ionization in intermediate keV He2+-H collisions
(1997-01-14)
Kuang, JY
;
Lin, CD
;
物理研究所
;
Institute of Physics
Our recently developed two-centre atomic orbital (TCAO) close-coupling method is applied to He2+-H(1s) collisions in the impact energy range from 20-400 keV amu(-1). Convergent cross sections are obtained for this system by using a large number of bound and pseudostate basis functions on the target and a limited number of bound states on the projectile. Cross sections for electron transfer to 1s, 2l, 3l, 4l and 5l, for excitation to 2l, 3l, 4l and 5l and for ionization are presented and compared with available experimental data and other theoretical calculations. The accuracy of the previous TCAO close-coupling calculations is challenged and the reliability of some experimental data for this system is questioned.
Coulomb trajectory effects on electron-impact detachment of negative ions and on mutual neutralization cross sections
(1996-12-28)
Lin, JT
;
Jiang, TF
;
Lin, CD
;
電子物理學系
;
物理研究所
Cross sections of electron-impact detachment of negative ions and of mutual neutralization between positive and negative ions are calculated using a model based on the semiclassical theory for ion-atom collisions but modified to include Coulomb trajectory effects. It is shown that the method allows us to obtain accurate results for collisions down to low energies. The Coulomb repulsion between the electron and the negative ion accounts for the rapid decrease of detachment cross sections at low energies, and the Coulomb attraction between positive and negative ions accounts for the rapid increase of neutralization cross sections at low velocities.
Electron detachment of H- in collision with Ne4+ and Ar4+ ions
(1997-09-01)
Lin, JT
;
Jiang, TF
;
Kuang, JY
;
Lin, CD
;
電子物理學系
Total-electron detachment cross sections for H- colliding with multiply charged Ne4+ and Ar4+ ions are calculated using the two-center atomic-orbital close-coupling expansion method in the center-of-mass energy range of 4-200 keV. The calculation shows that there is no core effect, and that electron capture only plays a minor role for energies above 20 keV. At 50 keV, where electron capture is not important, the single-center atomic-orbital expansion method was used to calculate the detachment cross sections for incident charges q=1-8. The present calculations are shown to be in good agreement with experimental data.
Hyperspherical approach to three-electron atomic systems
(1996-06-01)
Yang, XZ
;
Bao, CG
;
Lin, CD
;
物理研究所
;
Institute of Physics
The hyperspherical coordinates approach to three-electron atomic systems is further refined by taking into account the symmetry of the electrons analytically. Spins are treated explicitly for both doublet and quartet cases to reduce the three-electron Schrodinger equation to a set of coupled two-dimensional partial differential equations in a compact, symmetric form ready for numerical calculations. It is shown that the resulting equations can be accurately solved using B splines. By adopting the adiabatic approximation, the hyperspherical potential curves for singly, doubly, and triply excited states for the P-2(o) symmetry of Li are obtained.
Hyperspherical approach to three-electron atomic systems
(1996-06-01)
Yang, XZ
;
Bao, CG
;
Lin, CD
;
物理研究所
;
Institute of Physics
The hyperspherical coordinates approach to three-electron atomic systems is further refined by taking into account the symmetry of the electrons analytically. Spins are treated explicitly for both doublet and quartet cases to reduce the three-electron Schrodinger equation to a set of coupled two-dimensional partial differential equations in a compact, symmetric form ready for numerical calculations. It is shown that the resulting equations can be accurately solved using B splines. By adopting the adiabatic approximation, the hyperspherical potential curves for singly, doubly, and triply excited states for the P-2(o) symmetry of Li are obtained.
Ionization of oriented elliptic Rydberg states by half-cycle pulses
(1997-03-01)
Jiang, TF
;
Lin, CD
;
物理研究所
;
Institute of Physics
We calculate the ionization of elliptic Rydberg states by half-cycle unipolar electromagnetic-field pulses and examine the dependence of ionization probabilities on the eccentricity and the orientation of the ellipse with respect to the field direction of the pulse. It is suggested that the predicted large geometrical dependences be tested experimentally.
One- and two-electron transitions in slow C5+-He collisions: Total and angle-differential cross sections and coherence parameters
(1996-12-01)
Fritsch, W
;
Lin, CD
;
物理研究所
;
Institute of Physics
Transitions of one or two electrons in C5+-He collisions are studied within the semiclassical close-coupling description of atomic collisions, at impact energies of 1-35 keV/u. Angle-integrated cross sections are determined for single-transfer, double-transfer, and transfer-excitation channels. For single capture to 3p states and for two final states in the two-electron transfer channel, angle-differential cross sections are derived and a number of coherence parameters that depend on the quantum-mechanical phases are calculated. The results are compared with recent data on angle-differential two-electron transfer and with results from an earlier theoretical study.
One- and two-electron transitions in slow C5+-He collisions: Total and angle-differential cross sections and coherence parameters
(1996-12-01)
Fritsch, W
;
Lin, CD
;
物理研究所
;
Institute of Physics
Transitions of one or two electrons in C5+-He collisions are studied within the semiclassical close-coupling description of atomic collisions, at impact energies of 1-35 keV/u. Angle-integrated cross sections are determined for single-transfer, double-transfer, and transfer-excitation channels. For single capture to 3p states and for two final states in the two-electron transfer channel, angle-differential cross sections are derived and a number of coherence parameters that depend on the quantum-mechanical phases are calculated. The results are compared with recent data on angle-differential two-electron transfer and with results from an earlier theoretical study.