Considerations on the partial Patterson function of superstructures

The characteristics of the “partial Patterson function”, i.e. a Fourier summation of |F(h)|2using superstructure reflections only, is analyzed by means of a newly introduced d-function (“disturbance function”). By considering the Fourier transform of the d-function, the symmetry of partial Patterson is understood: the reasons for existence of negative peaks and their meaning are treated. The Patterson function of superlattice structure is furthermore divided into three components, and the symmetry of each map and relations between them are discussed.