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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 34, Number 11
BKCSDE 34(11)
November 20, 2013 

A Variant of the Brillouin-Wigner Perturbation Theory with Epstein-Nesbet Partitioning
Sangyoub Lee*, Cheol Ho Choi, Eunji Kim, Young Kyun Choi
Perturbation theory
We present an elementary pedagogical derivation of the Brillouin-Wigner and the Rayleigh-Schrödinger perturbation theories with Epstein-Nesbet partitioning. A variant of the Brillouin-Wigner perturbation theory is also introduced, which can be easily extended to the quasi-degenerate case. A main advantage of the new theory is that the computing time required for obtaining the successive higher-order results is minimal after the third-order calculation. We illustrate the accuracy of the new perturbation theory for some simple model systems like the perturbed harmonic oscillator and the particle in a box.
3279 - 3283
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