Anisotropic Temperature Factors in Cubic Crystals

Abstract

IN recent structure analyses of crystals it has been found impossible to obtain reliable atomic co-ordinates unless allowance is made for anisotropic thermal vibration of the individual atoms¹. It has, of course, long been known that different atoms have different amplitudes of vibration even in cubic structures². Weiss, DeMarco, Weremchuk, Corliss and Hastings³ have recently reported that the Debye factors for the 222 and 400 reflexions from α-brass are different, and they have asked how this can be, since they interpret Ott's theory⁴ as implying that the Debye factor for reflexions from a cubic crystal should be independent of crystallographic direction.