Orientational disorder in the cubic phase of ΚΝO₂

Abstract

We analyse X-ray single crystal data taken at Τ = 393 Κ from the high temperature phase of KN0 2 I. Two models are used to describe the orientationally disordered N0 2 molecules: a Frenkel model made up from two sets of 24 discrete settings of the N0 2 group, and a continuous distribution model using symmetry adapted functions.Both models are compatible with anisotropic mass distributions centered around the molecular center of mass (COM) as a fixed point. We conclude from both numerical and dynamical reasons that the N0 2 disorder in KN0 2 1 is dynamical i. e. that the continuous model applies in this case. * Also as guest at the Hahn-Meitner-Institut,