Hidden structure in amorphous solids

TL;DR

This paper investigates subtle structural correlations in amorphous solids, revealing that similar bond-length correlations exist across different materials, which may influence their electronic properties.

Contribution

It demonstrates the presence of bond-length correlations in amorphous SiO2 and organic molecules, extending previous findings in amorphous silicon and discussing their potential generality.

Findings

Bond-length correlations exist in amorphous SiO2

Similar correlations are found in organic molecules

These structures may affect electronic properties

Abstract

Recent theoretical studies of amorphous silicon [Y. Pan et al. Phys. Rev. Lett. 100 206403 (2008)] have revealed subtle but significant structural correlations in network topology: the tendency for short (long) bonds to be spatially correlated with other short (long) bonds). These structures were linked to the electronic band tails in the optical gap. In this paper, we further examine these issues for amorphous silicon, and demonstrate that analogous correlations exist in amorphous SiO2, and in the organic molecule, b-carotene. We conclude with a discussion of the origin of the effects and its possible generality.