Sensitivity of cross sections to the diffuseness of the confining potential in time-dependent close-coupling calculations of the double photoionization of He@C60

2013 ◽  
Vol 87 (1) ◽  
Author(s):  
Teck-Ghee Lee ◽  
J. A. Ludlow ◽  
M. S. Pindzola
Keyword(s):  
Cross Sections ◽  
Time Dependent ◽  
Close Coupling ◽  
Confining Potential ◽  
Double Photoionization

scholarly journals Electron-impact ionization of the Pb atom

2021 ◽  
Vol 75 (2) ◽  
Author(s):  
M. S. Pindzola ◽  
S. D. Loch ◽  
J. P. Colgan
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Impact Ionization ◽  
Polarization Potential ◽  
Time Dependent ◽  
Experimental Measurements ◽  
Ionization Cross ◽  
Close Coupling ◽  
Direct Ionization ◽  
Ionization Cross Sections

Abstract Electron-impact ionization cross sections are calculated for the ground configuration of the Pb atom. Time-dependent close-coupling cross sections for the direct ionization of the 6s and 6p subshells leading to single ionization are calculated with and without a polarization potential. Configuration-average distorted-wave cross sections for the direct ionization of the 6s and 6p subshells leading to single ionization are also calculated with and without a polarization potential. We find the time-dependent close-coupling cross sections using a polarization potential to be in good agreement with convergent-close-coupling cross sections using a polarization potential. The total direct ionization cross sections are compared to two sets of experimental measurements. The differences between the direct ionization cross sections and the experimental measurements are mainly due to indirect ionization cross sections coming from the $$6s^2 6p^2 \rightarrow 6s 6p^3$$ 6 s 2 6 p 2 → 6 s 6 p 3 excitation followed by autoionization. GraphicAbstract

scholarly journals Electron-Impact Ionization of Heavy Atoms Using the Time-Dependent Close-Coupling Method

Atoms ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 32
Author(s):  
Michael S. Pindzola ◽  
Stuart D. Loch ◽  
James P. Colgan
Keyword(s):  
Electron Impact ◽  
Cross Sections ◽  
Impact Ionization ◽  
Coupling Method ◽  
Time Dependent ◽  
Ionization Cross ◽  
Close Coupling ◽  
Direct Ionization ◽  
Total Ionization ◽  
Ionization Cross Sections

The time-dependent close-coupling method has been recently applied to calculate electron-impact direct ionization cross sections for the Kr, W, and Pb atoms. An overview is presented for these three heavy neutral atom systems. When the direct ionization cross sections are combined with excitation-autoionization cross sections, the total ionization cross sections were found to be in reasonable agreement with crossed-beams measurements for Kr and Pb.

Rotational de-excitations of C3H+ (1Σ+) by collision with He: new ab initio potential energy surface and scattering calculations

2020 ◽  
Vol 494 (4) ◽  
pp. 5675-5681 ◽  
Author(s):  
Sanchit Chhabra ◽  
T J Dhilip Kumar
Keyword(s):  
Potential Energy ◽  
Potential Energy Surface ◽  
Ab Initio ◽  
Cross Sections ◽  
Energy Surface ◽  
Molecular Ions ◽  
Basis Set ◽  
Rate Coefficients ◽  
Close Coupling ◽  
Collisional Rate Coefficients

ABSTRACT Molecular ions play an important role in the astrochemistry of interstellar and circumstellar media. C3H+ has been identified in the interstellar medium recently. A new potential energy surface of the C3H+–He van der Waals complex is computed using the ab initio explicitly correlated coupled cluster with the single, double and perturbative triple excitation [CCSD(T)-F12] method and the augmented correlation consistent polarized valence triple zeta (aug-cc-pVTZ) basis set. The potential presents a well of 174.6 cm−1 in linear geometry towards the H end. Calculations of pure rotational excitation cross-sections of C3H+ by He are carried out using the exact quantum mechanical close-coupling approach. Cross-sections for transitions among the rotational levels of C3H+ are computed for energies up to 600 cm−1. The cross-sections are used to obtain the collisional rate coefficients for temperatures T ≤ 100 K. Along with laboratory experiments, the results obtained in this work may be very useful for astrophysical applications to understand hydrocarbon chemistry.

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