The Kadanoff-Baym approach to double excitations in finite systems
Säkkinen, N., Manninen, M., & van Leeuwen, R. (2012). The Kadanoff-Baym approach to double excitations in finite systems. New Journal of Physics, 14(13032). https://doi.org/10.1088/1367-2630/14/1/013032
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© IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
We benchmark many-body perturbation theory by studying neutral,
as well as non-neutral, excitations of finite lattice systems. The neutral excitation
spectra are obtained by time-propagating the Kadanoff–Baym equations in the
Hartree–Fock and the second Born approximations. Our method is equivalent to
solving the Bethe–Salpeter equation with a high-level kernel while respecting
self-consistency, which guarantees the fulfillment of a frequency sum rule. As
a result, we find that a time-local method, such as Hartree–Fock, can give
incomplete spectra, while already the second Born approximation, which is the
simplest time-non-local approximation, reproduces well most of the additional
excitations, which are characterized as double excitations.
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Except where otherwise noted, this item's license is described as © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
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