title: Relativistic and QED corrections for the beryllium atom.
abstract: Complete relativistic and quantum electrodynamics corrections of order alpha(2) Ry and alpha(3) Ry are calculated for the ground state of the beryllium atom and its positive ion. A basis set of correlated Gaussian functions is used, with exponents optimized against nonrelativistic binding energies. The results for Bethe logarithms ln(k(0)(Be)=5.750 34(3) and ln(k(0)(Be+)=5.751 67(3) demonstrate the availability of high precision theoretical predictions for energy levels of the beryllium atom and light ions. Our recommended value of the ionization potential 75 192.514(80) cm(-1) agrees with equally accurate available experimental values.
authors.affiliation: Institute of Theoretical Physics, Warsaw University, Hoza 69, 00-681 Warsaw, Poland. krp@fuw.edu.pl
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Pachucki
authors.forename: Jacek
authors.initials: J
authors.lastname: Komasa