The structure of expanded mercury

The structure of expanded mercury along its liquid-vapour coexistence curve has been studied in detail by applying the reverse Monte Carlo modelling technique to the x-ray diffraction data on Tamura and Hosokawa (Tamura K and Hosokawa S 1994 J. Phys.: Condens. Matter 6 A241). The models suggest that as the density decreases there is an initial change from a more close-packed to a less close-packed structure. Whilst most atom pairs retain the same near-neighbour distance, of about 3.0 A, a few change to having a slightly larger neighbour distance of about 3.7 A. At the lower densities many atoms have a very low coordination, indicating that they are on the edges of clusters, or on 'pathways' between clusters.