THIS INFORMATION IS OBSOLETE AND IS PROVIDED ONLY FOR ITS HISTORICAL VALUE

by J. C. Caillat and L. S. Bartell, Department of Chemistry, The University of Michigan, Ann Arbor, Michigan 48109

The purpose of this program is to provide a means of analyzing complex Debye-Scherrer patterns in cases in which standard procedures cannot avoid becoming ensnared in the many local least-squares minima. To assist in the discrimination of the true from false minima, the present scheme entails the fitting of a pattern of intensities rather than of line positions. Tentative assignments of diffraction lines never need to be made, nor do diffraction features even need to be resolved if the intensity profile provides enough distinct features to establish the (at maximum) six- cell parameters.Because intensities must be calculated for comparison with experimental intensities, it is necessary to have a plausible initial guess of atomic positions in order to calculate structurefactors. This hasbeen generated with the aid of PCK6 by D. E. Williams (QCPE 373). Initial values of cell parameters and atomic positions are afforded by PCK6. As cell parameters refine in POWDRFIT, atomic positions can be updated from time to time, if necessary, by imposing experimental cell parameters as constraints in PCK6.

FORTRAN 77 Lines of Code: 1791