Figure 5
Structures of methane: (a) illustration of possible sites around the icosahedra, (b) 21-molecule rhombohedral methane, with F1, F2, F3, F4 sites occupied; (c) view of the icosahedron packing in the rhombohedral methane (space group: ). Two C sublattices are marked by different colors in a 21-molecule cell (non-icosahedral, green; icosahedral, grey). |