https://doi.org/10.1140/epjd/e2010-10500-9
On highly accurate calculations of the excited n1S(L = 0)-states in helium atoms
Department of Chemistry, University of Western Ontario, N6A 5B7 London, Ontario, Canada
Corresponding authors: a afrolov@uwo.ca - b dwardlaw@uwo.ca
Received:
10
September
2010
Revised:
12
November
2010
Published online:
14
January
2011
The total energies and various bound state properties of the excited 21S(L
= 0)-states in two-electron helium atoms, including the 
,
and 
atoms, are determined to very high numerical accuracy.
The convergence of the results obtained for some electron-nuclear and
electron-electron expectation values and, in particular, for the
electron-nuclear and electron-electron cusp values, is discussed. The field
component of the isotope shift and lowest order QED correction are estimated
for the 21S(L = 0)-states in the 4He and 3He atoms. We also
apply our highly accurate methods to numerical computations of the excited
n1S-states (for n = 3 and 4) in two-electron atomic systems.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2011
