DENSE AND RARE 4-CONNECTED NETS

Topological and geometrical properties of some 4-connected nets with one kind of vertex and with special properties are described. They are those that have high or low numbers of nth neighbors, and the regular and quasi-regular nets which have all vertices and all edges equivalent. A rare stable sphere packing, that is rarer than that of Heesch and Laves, is described. A new net with only two vertices in the topological repeat unit is identified in the crystal structure of CdSO4. A net with three vertices in the repeat unit which contains no circuits smaller than 7 is also described. Methods for characterization of the topology of nets are discussed.