In conclusion then, this brief survey has sought to bring together just some of the diverse problems that are now tractable from a computational point of view. In the forseeable future two areas stand out as ripe for further progress. They are:(i)
The development of improved solid state potentials, including many body effects and refinements to the shell model
(ii)
The application of defect lattice methods to extended defects such as grain boundaries, stacking faults and shear planes.
The second, in particular, could find wide application in many important areas of solid state science and technology.