Neutron diffuse scattering in the disordered phase of CBr4. II. Theoretical evidence of steric hindrance

Abstract

For pt.I see ibid., vol.13, p.2833 (1980). The object of the paper is the study of the intermolecular correlations in the orientationally disordered phase of Cbr₄. It is shown that, contrary to what takes place in the plastic phase of methane, very strong correlations of steric origin occur between disordered molecules. The theoretical calculation of the diffuse scattering, based on a graphical series expansion in the Q vector, shows that the correlations of steric origin produce an intense cigar-shaped diffuse scattering, centred near (2.1, -2.1, 0) and oriented along the (111)* direction. This is in good accordance with the known experiments.