Аннотация:
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