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arXiv · 0909.5542

Ground state of Li and Be$^+$ using explicitly correlated functions

Mariusz Puchalski·Dariusz Kedziera·Krzysztof Pachucki
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Abstract

We compare the explicitly correlated Hylleraas and exponential basis sets in the evaluations of ground state of Li and Be$^+$. Calculations with Hylleraas functions are numerically stable and can be performed with the large number of basis functions. Our results for ground state energies $-7.478 060 323 910 10(32)$, $-14.324 763 176 790 43(22)$ of Li and Be$^+$ correspondingly, are the most accurate to date. When small basis set is considered, explicitly correlated exponential functions are much more effective. With only 128 functions we obtained about $10^{-9}$ relative accuracy, but the severe numerical instabilities make this basis costly in the evaluation.

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Mariusz Puchalski, Dariusz Kedziera, Krzysztof Pachucki. 2009-09-30. Ground state of Li and Be$^+$ using explicitly correlated functions. https://doi.org/10.1103/physreva.80.032521

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