Representation of the potential energy surface

For any of the transitions of any of the types of point defects, an activation energy must be supplied by the user. This energy may depend on the atomic structure of the immediate environment of the defect up to some distance, and so there may be a very large number of different activation energies that need to be explicitly listed. These energies are supplied in the format of library files which contain a list of 'entries', each of which describes a particular structure surrounding a defect or undercoordinated atom. For each structure, there follows a list of energies for the different types of transition possible for that defect. When the code is run, each interstitial atom and undercoordinated lattice atom in the system is found, and then matched to a library file entry. The energies for the allowed transitions are then added to the event list. If a library entry is not found to match a defect local structure, then the code exits with an error and prints a schematic of the unmatched structure which can then be added to the library as required.