Theory and energetics of mass spectra (original) (raw)

Ab initio Self-consistent Field Calculations including Electron Correlation.-An important distinction must be drawn between ab initio SCF calculations using extended basis sets and those using minimal basis Only the former are expected to give results of Hartree-Fock accuracy in the single-particle approximation (which ignores electron correlation). These calculations are very expensive for polyatomic molecules, and minimal basis set calculations are therefore more generally performed. With judicious choice of basis functions for particular systems, results within a few kcal mol-' of the Hartree-Fock limit can be obtained using minimal basis sets.5 But even with results of this accuracy erroneous conclusions may be drawn because electron correlation is ignored in the Hartree-Fock