All-electron explicitly correlated calculations of S- and P-states of beryllium atom

We report new benchmark calculations of several lowest S- and P-states of Be atom carried out in the framework of the variational method that employs large and highly optimized all-particle explicitly correlated Gaussian basis sets. In the calculations we include the effects due to finite nuclear mass as well as the leading relativistic and QED corrections. A comparison of the computed transition energies with experimentally derived values is made and the sources of the remaining discrepancies are discussed.