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arXiv · 0804.4697

Convergence of all-order many-body methods: coupled-cluster study for Li

A. Derevianko·S. G. Porsev·K. Beloy
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Abstract

We present and analyze results of the relativistic coupled-cluster calculation of energies, hyperfine constants, and dipole matrix elements for the $2s$, $2p_{1/2}$, and $2p_{3/2}$ states of Li atom. The calculations are complete through the fourth order of many-body perturbation theory for energies and through the fifth order for matrix elements and subsume certain chains of diagrams in all orders. A nearly complete many-body calculation allows us to draw conclusions on the convergence pattern of the coupled-cluster method. Our analysis suggests that the high-order many-body contributions to energies and matrix elements scale proportionally and provides a quantitative ground for semi-empirical fits of {\em ab inito} matrix elements to experimental energies.

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A. Derevianko, S. G. Porsev, K. Beloy. 2008-04-29. Convergence of all-order many-body methods: coupled-cluster study for Li. https://doi.org/10.1103/physreva.78.010503

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