Reading the structure of amorphous materials from diffraction patterns and neighbor distribution functions

An exact analytical expression for the static structure factor $S(k)$ in disordered materials is derived from Fourier transformed neighbor distribution decompositions in real space, and permits to reconstruct the function $S(k)$ in an iterative fashion. The result is successfully compared to experimental data of archetypal glasses or amorphous materials (GeS$_2$, As$_2$Se$_3$, GeTe), and links quantitatively knowledge of structural information on short and intermediate -range order with the motifs found on the diffraction patterns in reciprocal space. The approach furthermore reveals that only a limited number of neighbor shells is sufficient to reasonably describe the structure factor for $k>$2~\AA$^{-1}$. In the limit of the high momentum transfer, the oscillation characteristics of the interference function are related with new informations on the short-range order of disordered materials.