Analysis of structural characteristics of chemical compounds in a large computer-based file. Part II. Atom-centred fragments

A file of structures from the Chemical Abstracts Service Registry System has been analysed to determine the distribution of a number of different types of atom-centred structural fragments. The largest fragments studied were augmented atoms containing up to five atoms and four bonds. The effects which differentiating between cyclic and acyclic bonds and varying the size of fragments have on the fragment distributions have been examined.