Three lowest S states of 9Be+ calculated with including nuclear motion and relativistic and QED corrections

Abstract

We have performed high-accuracy quantum mechanical calculations for the three lowest S states of the beryllium ion 9Be+ . The nonrelativistic part of the calculations was done with the variational approach and explicitly included the nuclear motion i.e., the finite-nuclear-mass approach . The nonrelativistic wave functions were expanded in terms of explicitly correlated Gaussian functions. These nonrelativistic functions were subsequently used to calculate the leading 2 relativistic corrections =1/c and the 3 and 4 QED quantum electrodynamics corrections. In the 4 QED correction we only accounted for its dominant component typically contributing about 80% of the correction. With those the present results are the most accurate ever obtained for 9Be+. They also agree with the experimentally measured transitions within less than 0.1 cm−1