THE ATOMIC CORRELATION OPERATOR METHOD

Atomic correlation operators are introduced which provide a method of selecting configurations for the description of correlations. When the calculations are done to lowest order in the residual interactions their accuracy can be checked by comparing them with Moller-Plesset perturbation calculations. A subset of the atomic correlation operators generates interatomic correlations. When the latter are treated better than by lowest-order perturbation theory the computational results can be compared with those of a coupled-electron-pair approximation (zero) calculation. The method is tested by applying it to CH4.