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arXiv · 2105.05009

Explicit diagrammatic solution of normalised, nondegenerate Rayleigh-Schr\"odinger perturbation theory

Joel C. Pommerening·David P. DiVincenzo
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Abstract

We solve the coupled recurrence relations for eigenenergies and -vectors in nondegenerate Rayleigh-Schr\"odinger perturbation theory under the constraint that the approximate eigenvector be normalised to $1$ in every order. The series can be expressed in terms of diagrams that were first introduced by C. Bloch [Nucl. Phys. 6, 329 (1958)] for the degenerate, unnormalised case. Normalisation increases the number of terms and introduces a nontrivial dependence on the diagrams' topology to the coefficients.

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Joel C. Pommerening, David P. DiVincenzo. 2021-05-11. Explicit diagrammatic solution of normalised, nondegenerate Rayleigh-Schr\"odinger perturbation theory. https://doi.org/10.1007/s00023-021-01150-0

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