THE COCHRAN DISTRIBUTION FOR INCOMMENSURATELY MODULATED STRUCTURES

摘要

The recently defined normalized structure factors [Lam, E.J.W., Beurskens, P.T. & Smaalen, S. van (1993).Acta Cryst. A49, 709-721] have been subjected to extensive tests regarding their applicability in direct methods for phase determination. It is shown that the distribution of the structure invariants p(-H)+q(H')+p(H-Hl), where H and H' are main and/or satellite reflections, approximately have the same functional form as the Cochran distribution. In general, triplet relations involving satellite reflections are less reliable than relations between main reflections only.