Vector Processing and Parallel Processing in Many—Body Perturbation Theory Calculations of Electron Correlation Effects in Atoms and Molecules

The accurate treatment of electron correlation effects is central to atomic and molecular physics and to modern quantum chemistry. Over recent years, the trend in the development of techniques for handling the effects of electron correlation in atoms and molecules has been towards an increasing significance of perturbation theory both in practical applications and in the analysis and comparision of methods used in contemporary studies of many—electron systems. The rising popularity of many—body perturbation theory for quantum chemical calculations which go beyond the Hartree—Fock model is attributable to both the theoretical and the computational properties of the method. It is the close connection between these two properties that we wish to emphasize here.