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Browsing Articles by Subject "beryllium atom"

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    Calculations of low-lying 1P states of the beryllium atom
    (2009) Bubin, Sergiy; Adamowicz, Ludwik
    High-accuracy nonrelativistic variational calculations employing explicitly correlated Gaussian basis functions have been performed to determine the energies and the expectation values of some operators for the lowest four 1P1 states of the beryllium atom. The states correspond to the electron configurations 1s22s1np1, where n=2, 3, 4, and 5. The calculations were performed for both finite and infinite mass of the Be nucleus. The basis set for each state was grown to the level of 5000 Gaussians. With that many functions we achieved a tight energy convergence. The reported values, to the best of our knowledge, are the most accurate ever obtained for the four states
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    Five lowest 1S states of the Be atom calculated with a finite-nuclear-mass approach and with relativistic and QED corrections
    (2009) Stanke, Monika; Komasa, Jacek; Bubin, Sergiy; Adamowicz, Ludwik
    We have performed very accurate quantum mechanical calculations of the five lowest S states of the beryllium atom. In the nonrelativistic part of the calculations we used the variational method and we explicitly included the nuclear motion in the Schrödinger equation. The nonrelativistic wave functions of the five states were expanded in terms of explicitly correlated Gaussian functions. These wave functions were used to calculate the leading 2 relativistic correction is the fine structure constant and the 3 quantum electrodynamics QED correction. We also estimated the 4 QED correction by calculating its dominant component. A comparison of the experimental transition frequencies with the frequencies obtained based on the energies calculated in this work shows an excellent agreement