Hartree-Fock Treatment of Exchange in (e, 2e) Collisions


The distorted-wave Born approximation has been very successful for treating electron-impact ionization (e, 2e) of heavy atoms for high-energy incident electrons. However, as the energy of the incident electrons approaches threshold, significant differences between experiment and theory are observed. In these calculations, the continuum projectile electron wavefunction is typically calculated using the static field of the atom plus a local approximation for electron exchange. While this approximation is believed to be reasonable for higher energies, it is likely to become unreliable for energies near threshold. Here we report a proper treatment of electron exchange in which a full Hartree-Fock calculation is performed for both the atomic and projectile electrons. For the initial state, the projectile orbitals are calculated in the Hartree-Fock approximation with full exchange with the target electrons and for the final state, the Hartree-Fock continuum orbitals are computed for an ion. It is found that the static-exchange approximation is not valid for lower incident energy projectiles.



Keywords and Phrases

Approximation theory; Atoms; Electron energy levels; Electrons; Ionization; Ions; Continuum projectile electron wavefunction; Distorted wave born approximation; Electron exchange; Electron impact ionization; Hartree-Fock approximation; Heavy atoms; Static field; Molecular physics

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Article - Journal

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© 1999 IOP, Bristol, United Kingdom, All rights reserved.

Publication Date

01 Oct 1999