Accurate elastic scattering factors for lithium to argon based on correlated wavefunctions

Elastic scattering factors (or atomic form factors) f(s) for Li to Ar have been derived in the first Born approximation from ab initio MR-SDCI (multireference singly and doubly excited configuration interaction) calculations which recover between 90 and 99% of the estimated total correlation energy. The correlation effects on f(s) are contrasted with the relativistic effects known from the literature. Atomic form factors are presented that take into account correlation and relativistic contributions in an additive manner. (orig.)