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Correlation and spin polarization in quantum dots: local spin density functional theory revisited

Correlation and spin polarization in quantum dots: local spin density functional theory revisited
Correlation and spin polarization in quantum dots: local spin density functional theory revisited
Using quantum dot artificial atoms as a simple toy model, we reflect on the question of whether spin density functional theory (SDFT) can accurately describe correlation effects in low-dimensional fermion systems. Different expressions for the local density approximation of the exchange-correlation energy for the two-dimensional electron gas, such as the much-used functional of Tanatar and Ceperley, and the recent suggestion by Attaccalite et al., are compared with the results of a numerical diagonalization of the many-body Hamiltonian matrix in the limit of small electron numbers. For systems with degeneracies, as shown in the present work for the example of a spin triplet with S = 1, the direct comparison with configuration interaction (CI) methods demonstrates that the spin representation of SDFT may, under certain circumstances, produce artificial energy splittings between states that belong to the same spin multiplet. For a singlet ground state with S = Sz = 0, however, the correlation functions of the CI solutions confirm the spin-density wave states found earlier within the SDFT method.
0020-7608
817-825
Borgh, M.
a3c181f8-0535-46cd-bb9a-6e930a81f86e
Toreblad, M.
d528fc15-6b6a-472d-ac06-79d0fe3c654d
Koskinen, M.
959081c6-d118-43de-96f8-9d7798c5c8c9
Manninen, M.
fd5106ea-6562-4c78-a65a-63f64c198fcb
Åberg, S.
ef94134b-9b1b-4b51-961d-688caf121243
Reimann, S. M.
8319a40d-552d-41f8-af7c-4674e9e4eb86
Borgh, M.
a3c181f8-0535-46cd-bb9a-6e930a81f86e
Toreblad, M.
d528fc15-6b6a-472d-ac06-79d0fe3c654d
Koskinen, M.
959081c6-d118-43de-96f8-9d7798c5c8c9
Manninen, M.
fd5106ea-6562-4c78-a65a-63f64c198fcb
Åberg, S.
ef94134b-9b1b-4b51-961d-688caf121243
Reimann, S. M.
8319a40d-552d-41f8-af7c-4674e9e4eb86

Borgh, M., Toreblad, M. and Koskinen, M. et al. (2005) Correlation and spin polarization in quantum dots: local spin density functional theory revisited. International Journal of Quantum Chemistry, 105 (6), 817-825. (doi:10.1002/(ISSN)1097-461X).

Record type: Article

Abstract

Using quantum dot artificial atoms as a simple toy model, we reflect on the question of whether spin density functional theory (SDFT) can accurately describe correlation effects in low-dimensional fermion systems. Different expressions for the local density approximation of the exchange-correlation energy for the two-dimensional electron gas, such as the much-used functional of Tanatar and Ceperley, and the recent suggestion by Attaccalite et al., are compared with the results of a numerical diagonalization of the many-body Hamiltonian matrix in the limit of small electron numbers. For systems with degeneracies, as shown in the present work for the example of a spin triplet with S = 1, the direct comparison with configuration interaction (CI) methods demonstrates that the spin representation of SDFT may, under certain circumstances, produce artificial energy splittings between states that belong to the same spin multiplet. For a singlet ground state with S = Sz = 0, however, the correlation functions of the CI solutions confirm the spin-density wave states found earlier within the SDFT method.

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Published date: 12 September 2005
Organisations: Applied Mathematics

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Local EPrints ID: 198759
URI: http://eprints.soton.ac.uk/id/eprint/198759
ISSN: 0020-7608
PURE UUID: df257945-60a2-4fb1-bcfa-4e493d3667c0

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Date deposited: 06 Oct 2011 14:13
Last modified: 14 Mar 2024 04:13

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Contributors

Author: M. Borgh
Author: M. Toreblad
Author: M. Koskinen
Author: M. Manninen
Author: S. Åberg
Author: S. M. Reimann

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