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 m odelling technique to the x-ray diffraction data of Tamura and Hosokaw a (Tamura K and Hosokawa S 1994 J. Phys.: Condens. Matter 6 A241). The models suggest that as the density decreases there is an initial chan ge from a more close-packed to a less close-packed structure. Whilst m ost atom pairs retain the same near-neighbour distance, of about 3.0 A ngstrom, a few change to having a slightly larger neighbour distance o f about 3.7 Angstrom. At the lower densities many atoms have a very lo w coordination, indicating that they are on the edges of clusters, or on 'pathways' between clusters.