Hylleraas-configuration-interaction analysis of the low-lying states in the three-electron Li atom and Be+ ion

Abstract

The total energies of twenty eight bound S-, P-, D-, F-, G-, H-, and I-states in the three-electron systems Li atom and Be+ ion, respectively, are determined with the use of the Configuration Interaction (CI) with Slater orbitals and L-S eigenfunctions, and the Hylleraas-configuration-interaction (Hy-CI) methods. We discuss the construction and selection of the configurations in the wave functions, optimization of the orbital exponents and advanced computational techniques. Finally, we have developed a very effective procedure which allows one to determine the energies of the excited states in three-electron atoms and ions to high accuracy by using compact wave functions. For the ground and low lying excited states our best accuracy with the Hy-CI method was approximately 1.10-6 a.u. and 1.10-4 a.u. for other excited states. Analogous accuracy of the CI method is substantially lower approximately 1.10-3 a.u. Many of the rotationally excited (bound) states in the three-electron Li atom and Be+ ion have never been evaluated to such an accuracy.

28 pages, 50 references, 9 tables and 0 figures

References in corpus (3)

• Relativistic, QED, and finite nuclear mass corrections for low-lying states of Li and Be${}^{+}$
• Ground state of Li and Be${}^{+}$ using explicitly correlated functions
• Compact and accurate variational wave functions of three-electron atomic systems constructed from semi-exponential radial basis functions

Cited by in corpus (5)

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• Using Koopmans' theorem for constructing basis sets: Approaching high Rydberg excited states of lithium with a compact Gaussian basis
• On the ß- decay in the Li-8 and Li-9 atoms