Density functional theory investigation of antiproton-helium collisions

Abstract

We revisit recent developments in the theoretical foundations of time-dependent density functional theory (TDDFT). TDDFT is then applied to the calculation of total cross sections for ionization processes in the antiproton-Helium collision system. The Kohn-Sham potential is approximated as the sum of the Hartree-exchange potential and a correlation potential that was proposed in the context of laser-induced ionization. Furthermore, some approaches to the problem of calculating the ionization probabilities from the density are discussed. Small projectile energies below 5keV are considered as well as those in the range from 5 to 1000 keV. Results are compared with former calculations and with experimental data. We find that the correlation potential yields no obvious improvement of the results over the exchange-only approximation where the correlation potential is neglected. Furthermore, we find the problem of calculating the desired observables crucial, introducing errors of at least the same order of magnitude as the correlation potential. For the case of small energies we find that trajectory effects play an important role: the ionization cross sections are enlarged significantly if curved instead of straight-line trajectories are used for the projectile motion.

8 pages, 9 figures

References in corpus (5)

• On the "Causality Paradox" of Time-Dependent Density Functional Theory
• Is time-dependent density functional theory formally exact?
• Adiabatic Approximation of the Correlation Function in the Density-Functional Treatment of Ionization Processes
• Fully Correlated Electronic Dynamics for Antiproton Impact Ionization of Helium
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Cited by in corpus (7)

• Exact time-dependent exchange-correlation potential in electron scattering processes
• Non-Adiabatic Approximations in Time-Dependent Density Functional Theory: Progress and Prospects
• Calculation of transition probabilities and ac Stark shifts in two-photon laser transitions of antiprotonic helium
• Ionization of helium by slow antiproton impact: total and differential cross sections
• The Exact Exchange-Correlation Potential in Time-Dependent Density Functional Theory: Choreographing Electrons with Steps and Peaks
• Exact time-dependent density functional theory for non-perturbative dynamics of helium atom
• Electron Emission in Antiproton-Hydrogen Interactions Studied with the One-Centre Basis Generator Method