During the last thirty years, with the development of high speed electronic computers, methods have evolved, which permit an accurate and quantitative, ab initio determina- tion of the electronic wavefunctions of atoms and molecules. Thus a detailed elucida- tion of the electronic energy and structure of molecules has become possible using quantum mechanics directly. Ho ever, it is necessary, if such calculations are to yield accurate and reliable results, to include electron correlation explicitely, which requires in general . configuration mixing procedures with an extremely large 5 number...
During the last thirty years, with the development of high speed electronic computers, methods have evolved, which permit an accurate and quantitative...