Moments of the Dipole Oscillator Strength Distribution and Mean ExcitationEnergies of Helium

摘要

The moments of the dipole oscillator strength distribution and the associatedmean excitation energies I have been calculated for the helium atom using the polarization-propagator formalism. It is found that, if correlation is included, agreement with experimental and other theoretical values is good. The moments of the dipole oscillator strength distribution (DOSD) of a system are of considerable interest, as they are related to many physically interesting quantities. As the interest in these quantities is high, there has been considerable effort expended in their determination. As the full excitation spectrum (both excitation energies and oscillator strengths) of the system is necessary to determine the moments, it is difficult to calculate them directly. Thus emphasis has been placed on ascertaining them semiempirically. In particular, Meath and coworkers have published a long series of papers reporting various properties of the DOSD's of various atoms and molecules (js)