Abstract
The effect of correlation on the one- and two-particle momentum distributions is analysed by using the natural expansion representation of a configuration-interaction space wavefunction. Several expectation values are reported with emphasis being given to two-electron properties. In particular, the angular and radial components of correlation are assessed by the determination of various correlation coefficients. The introduction of total angular correlation is found to increase the probability of the two momentum vectors being aligned-as is indicated by the positive values obtained for the angular correlation coefficients.