RELATIVISTIC X-RAY ELASTIC-SCATTERING FACTORS FOR NEUTRAL ATOMS Z=1-54 FROM MULTI-CONFIGURATION DIRAC-FOCK WAVE-FUNCTIONS IN THE 0-12 ANGSTROM(-1) SIN THETA LAMBDA RANGE, AND 6-GAUSSIAN ANALYTICAL EXPRESSIONS IN THE 0-6 ANGSTROM(-1) RANGE/

X-ray elastic scattering factors for the ground-state atoms H to Xe ha ve been calculated from the relativistic wavefunctions in the 0-12 Ang strom(-1) sin theta/lambda range and fitted in the 0-6 Angstrom(-1) si n theta/lambda range to a sum of six Gaussian functions for three diff erent sin theta/lambda ranges. More than one configuration was include d for elements with several electronic configurations having the same subshell occupancy. The resulting parameterized scattering factors are significantly more accurate than those previously published. Separate core-and valence-electron scattering values have also been obtained. The relativistic atomic energies, the atomic second moments and the li miting values of the electron scattering factor as sin theta/lambda ap proaches zero have been tabulated. The wavefunctions were calculated w ith the GRASP92 program package [Parpia, Froese Fischer & Grant (1996) . Comput. Phys. Commun. 94, 249-271] with the optimal level (OL) model rather than with the extended average level (EAL) model used in previ ous calculations [Rez, Rez & Grant (1994). Acta Cryst. A50, 481-497].