The incessant development of quantum chemistry since the appearance of the Schrodinger ] equation has turned this area into a respectable branch of science with unprecedented capabilities. It is now a well-recognized eld of research with pred- tive power that is an important component in physical chemical laboratories. Very important developments were conducted in the early days by bright theoretical s- entists that were ready to absorb the incredible and unpredicted computer revolution which was only just beginning. Isolated medium-size molecular systems can now be accurately studied...