A theoretical model for indirect dissociative electron attachment

Journal of Physical Chemistry A

Volumn 109, Issue 3, 2005, Pages 484-492

  Anusiewicz, Iwona ^a,b,c   Sobczyk, Monika ^a,b   Berdys Kochanska, Joanna ^a,b   Skurski, Piotr ^a,b   Simons, Jack ^a  

^a UNIVERSITY OF UTAH   (United States)

^b UNIVERSITY OF GDA SK   (Poland)

^c Found for Pol Science ^*

Author keywords

[No Author keywords available]

Indexed keywords

BOND LENGTH; ELECTRON ATTACHMENT; ELECTRON CAPTURE; METASTABLE ANIONS;

CHEMICAL BONDS; DISSOCIATION; ELECTRON ENERGY LEVELS; KINETIC ENERGY; MATHEMATICAL MODELS; NEGATIVE IONS; POTENTIAL ENERGY;

ELECTROCHEMISTRY;

EID: 13444254145     PISSN: 10895639     EISSN: None     Source Type: Journal    
DOI: 10.1021/jp046914f     Document Type: Article

References (22)

1. Dezarnaud-Dandine, C.; Bournel, F.; Troncy, M.; Jones, D.; Modelli, A. J. Phys. B: At. Mol. Opt. Phys. 1998, 31, L497-L502.
2. Pearl, D. M.; Burrow, P. D.; Nash, J. J.; Morrison, H.; Nachti-gallova, D.; Jordan, K. D. J. Chem. Phys. 1995, 99, 12379-12381. This paper contains a very nice discussion of how DEA yields can be used to probe the through-bond couplings that arise in such indirect DEA processes.
3. -15 s. These rates correspond to Heisenberg widths of 0.04-4 eV. Of course, the electron attachment efficiencies for E values lying within the Heisenberg widths of the resonance energy will not be uniform.
4. As noted in ref 3, both the * and π* anion states have significant Heisenberg uncertainties in their energies. In this paper, when we refer to an energy curve of one of these states we mean the central energy of that resonance state as a function of bond length. When we speak of the electron's kinetic energy that generates one of these states, we mean that the electron has an energy E lying within the Heisenberg width of that state we claim to be generated by electron capture.
5. Barrios, R.; Skurski, P.; Simons, J. J. Phys. Chem. B 2002, 106, 7991-7994.
6. Berdys, J.; Anusiewicz, I.; Skurski, P.; Simons, J. J. Phys. Chem. 2004, A108, 2999-3005.
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8. Berdys, J.; Skurski, P.; Simons, J. J. Phys. Chem. B 2004, 108, 5800-5805.
9. Anusiewicz I.; Berdys, J.; Sobczyk, M.; Skurski, P.; Simons, J. J. Phys. Chem. A 2004, 108, 11381-11387.
10. Miertus, S.; Tomasi, J. Chem. Phys. 1982, 65, 239-242. Cossi, M.; Barone, V.; Cammi, R.; Tomasi, J. Chem. Phys. Lett. 1996, 255, 327-335.
11. Miertus, S.; Tomasi, J. Chem. Phys. 1982, 65, 239-242. Cossi, M.; Barone, V.; Cammi, R.; Tomasi, J. Chem. Phys. Lett. 1996, 255, 327-335.
12. Of course, at even larger R values, a minimum can develop in these curves because of the long-range charge-dipole and charge-induced-dipole interactions.
13. Even if one uses nonvariational methods such as Møller-Plesset perturbation theory (MPn) or coupled-cluster theory (CC) to compute the neutral and anion energies, an initial step in such calculations involves performing a Hartree-Fock self-consistent field (SCF) calculation to obtain appropriate orthonormal molecular Orbitals. Because SCF calculations are variational, it is at this step that the collapse most likely occurs.
14. Hazi, A. U.; Taylor, H. S. Phys. Rev. A1 1970, 1109. Simons, J. J. Chem. Phys. 1981, 75, 2465; Frey, R. F.; Simons, J. J. Chem. Phys. 1986, 84, 4462.
15. Hazi, A. U.; Taylor, H. S. Phys. Rev. A1 1970, 1109. Simons, J. J. Chem. Phys. 1981, 75, 2465; Frey, R. F.; Simons, J. J. Chem. Phys. 1986, 84, 4462.
16. Hazi, A. U.; Taylor, H. S. Phys. Rev. A1 1970, 1109. Simons, J. J. Chem. Phys. 1981, 75, 2465; Frey, R. F.; Simons, J. J. Chem. Phys. 1986, 84, 4462.
17. For example, to evaluate the energy of a metastable state at one value of R, we need to carry out a series of calculations (typically 4-10) in which we have added a stabilizing potential of varying strength to the anion's molecular framework. By then extrapolating our findings to zero strength of this stabilizing potential, we achieve our estimate of the metastable state's energy. Each of these 4-10 calculations is at least as computationally demanding as calculating the energy of the corresponding neutral or its anion at R values where the anion is electronically bound.
18. c is the value of R at which the * energy intersects the neutral's energy curve and A, C, and b are parameters whose values we obtained by least-squares fitting. It turns out that the functions thus obtained represent very well the * anion's energy at shorter R values where this state is electronically metastable. We verified this by performing the time-consuming stabilization calculations on these * states at several R values to test the quality of the above exponential functional form.
19. We realize that this coupling is most likely R-dependent. However, to form a model that contains the fewest parameters, we assume that this matrix element is a constant. Of course, the ultimate judge for this assumption will be to see how well this model works.
20. - at such an R value.
21. We could have evaluated the upper adiabauc surface's energy and used it in the quadratic equation to determine |V|. but the lower adiabatic energy is almost always computationally easier to determine.
22. In such a calculation, all other geometrical degrees of freedom are relaxed to minimize the energy. Of course, in doing such a relaxation, one can also notice which geometrical degrees of freedom are changed most.