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Diagonalisation of the Dirac Hamiltonian as a basis for a relativistic many-body procedure

Heully, Jean Louis ; Lindgren, Ingvar ; Lindroth, Eva ; Lundqvist, Stig and Martensson-Pendrill, Ann Marrie LU orcid (1986) In Journal of Physics B: Atomic and Molecular Physics 19(18). p.2799-2815
Abstract

A diagonalisation procedure of the Foldy-Wouthuysen type is considered for the single-electron Dirac Hamiltonian as a basis for many-body applications. A modified procedure is suggested. In the diagonalisation procedure the Dirac equation is completely decoupled into two equations of the Pauli type. The expressions for positive- and negative-energy projection operators in the transformed basis are then trivial and, by performing the inverse transformation, projection operators for Dirac functions are obtained. Applying a similar transformation to the two-electron Dirac-Coulomb Hamiltonian leads to a diagonalised single-electron part and a non-diagonal two-electron interaction. In principle, the effect of the exchange of virtual,... (More)

A diagonalisation procedure of the Foldy-Wouthuysen type is considered for the single-electron Dirac Hamiltonian as a basis for many-body applications. A modified procedure is suggested. In the diagonalisation procedure the Dirac equation is completely decoupled into two equations of the Pauli type. The expressions for positive- and negative-energy projection operators in the transformed basis are then trivial and, by performing the inverse transformation, projection operators for Dirac functions are obtained. Applying a similar transformation to the two-electron Dirac-Coulomb Hamiltonian leads to a diagonalised single-electron part and a non-diagonal two-electron interaction. In principle, the effect of the exchange of virtual, transverse photons (Breit interactions) can also be included in the electron-electron interaction and transformed in a similar way. It is indicated how a diagonalisation procedure of this kind can be used as a basis for relativistic many-body calculations in the coupled cluster formulation in analogy with the corresponding non-relativistic procedure.

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author
; ; ; and
publishing date
type
Contribution to journal
publication status
published
in
Journal of Physics B: Atomic and Molecular Physics
volume
19
issue
18
article number
011
pages
17 pages
publisher
IOP Publishing
external identifiers
  • scopus:34547149847
ISSN
0022-3700
DOI
10.1088/0022-3700/19/18/011
language
English
LU publication?
no
id
1aedea75-c1e2-4fb6-b8fb-7bf29ebb3e4c
date added to LUP
2025-08-30 07:18:46
date last changed
2025-09-02 15:22:16
@article{1aedea75-c1e2-4fb6-b8fb-7bf29ebb3e4c,
  abstract     = {{<p>A diagonalisation procedure of the Foldy-Wouthuysen type is considered for the single-electron Dirac Hamiltonian as a basis for many-body applications. A modified procedure is suggested. In the diagonalisation procedure the Dirac equation is completely decoupled into two equations of the Pauli type. The expressions for positive- and negative-energy projection operators in the transformed basis are then trivial and, by performing the inverse transformation, projection operators for Dirac functions are obtained. Applying a similar transformation to the two-electron Dirac-Coulomb Hamiltonian leads to a diagonalised single-electron part and a non-diagonal two-electron interaction. In principle, the effect of the exchange of virtual, transverse photons (Breit interactions) can also be included in the electron-electron interaction and transformed in a similar way. It is indicated how a diagonalisation procedure of this kind can be used as a basis for relativistic many-body calculations in the coupled cluster formulation in analogy with the corresponding non-relativistic procedure.</p>}},
  author       = {{Heully, Jean Louis and Lindgren, Ingvar and Lindroth, Eva and Lundqvist, Stig and Martensson-Pendrill, Ann Marrie}},
  issn         = {{0022-3700}},
  language     = {{eng}},
  number       = {{18}},
  pages        = {{2799--2815}},
  publisher    = {{IOP Publishing}},
  series       = {{Journal of Physics B: Atomic and Molecular Physics}},
  title        = {{Diagonalisation of the Dirac Hamiltonian as a basis for a relativistic many-body procedure}},
  url          = {{http://dx.doi.org/10.1088/0022-3700/19/18/011}},
  doi          = {{10.1088/0022-3700/19/18/011}},
  volume       = {{19}},
  year         = {{1986}},
}