This chapter presents the Kohn-Sham approach to Density Functional Theory on which the calculations performed are based. The techniques used in the efficient solution of the equations derived are described and the application of these to aperiodic systems is discussed. A detailed description of these may be found in [1] and [2].
When combined, the methods described here provide a powerful tool for performing ab initio quantum mechanical calculations on an enormously diverse range of systems. Currently calculations may be performed on systems containing many tens of atoms on desktop workstations and several hundred atoms on parallel supercomputers. The current rate of growth in computing power implies that these figures will increase rapidly in the near future.