Numerical structure factor calculation of orientationally disordered molecules

The structure factor of librating or orientationally disordered molecules with isotropic Gaussian distribution functions is calculated exactly by numerical integration. The computer program with an example is described. The results are compared with approximation methods which correspond to a cumulant expansion of the structure factor. The application to the refinement of the plastic phases of C₂Cl₆ and SF₆ is shown. The influence of anharmonic distributions is considered. The method is compared to the analysis with spherical cubic harmonics.