Prepeak in the structural factor. Inhomogeneous packings of Lennard-Jones atoms

This work reports on the effects of structural inhomogeneities within the models of spherical atomic packings on the radial distribution function (RDF) and the structural factor (SF). Models of inhomogeneous packings were constructed by removing some atoms from homogeneous packing according to a predetermined template. Thus various additional voids, leading to specific structural correlations of atoms on a middle scale (several atomic sizes), are introduced in the model. A dense noncrystalline packing of 27,000 Lennard-Jones atoms serves as the initial system. Three various templates were used, and models containing different fractions of additional voids were constructed with each of these templates. It is demonstrated that RDF is only slightly sensitive to such inhomogeneities; in contrast, the SF has additional peaks at small q, these peaks being notable even after removal of a small fraction of atoms. Some models yield a single narrow prepeak, which is akin to that observed in diffraction experiment for some glasses.