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A quasidegenerate formulation of the second order n-electron valence state perturbation theory approach

Angeli, Celestino, Borini, Stefano, Cestari, Mirko, Cimiraglia, Renzo·2004·The Journal of Chemical Physics

Abstract

The n-electron valence state perturbation theory (NEVPT) is reformulated in a quasidegenerate (QD) approach. The new theory allows the treatment of cases where the proximity of the energies causes artifacts in the zero order description. Problems of quasidegeneration are relevant in the dynamics involving regions at avoided crossings (or conical intersections) and in spectroscopy where the energies and oscillator strengths can be strongly influenced by the mixing of states of different nature. Two test cases are analyzed concerning (a) the ionic-neutral avoided crossing in LiF and (b) the valence/Rydberg mixing in the excited states of ethene. The QD-NEVPT2 is shown to be a useful tool for such systems.

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Metadata

Authors
Angeli, C., Borini, S., Cestari, M., & Cimiraglia, R.
Venue
The Journal of Chemical Physics
Published
2004-09-01
Volume
121
Issue
9
Pages
4043-4049
ISSN
  • 0021-9606 (ISSN-L)
  • 1089-7690
OpenAlex
W1964027788
Cited by
412
References
0
FWCI
2.66
Type
journal article
Language
en
Open access
closed

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CoChat. (2026). Citation check: A quasidegenerate formulation of the second order n-electron valence state perturbation theory approach. https://app.cochat.ai/papers/10.1063/1.1778711
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Angeli, C., Borini, S., Cestari, M., & Cimiraglia, R. (2004). A quasidegenerate formulation of the second order n-electron valence state perturbation theory approach. The Journal of Chemical Physics. https://doi.org/10.1063/1.1778711

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