Coherent and Incoherent X-Ray Scattering by Bound Electrons. I. Helium Isoelectronic Sequence

Atomic form factors and incoherent scattering functions for the helium isoelectronic sequence through $Z=10\mathrm{}$ have been calculated with correlated ground-state wave functions. The wave functions are 120-term configuration-interaction expansions which give total ground-state energies differing from the most accurate available values by 0.02% for He i and 0.0007% for Ne ix. Comparison with published accurate calculations for helium indicates that the scattering factors, both coherent and incoherent, for the other members of the isoelectronic sequence, should be correct to at least three, and probably four, significant figures.