MOMENTUM-SPACE AND COULOMB CORRELATION - A 2-PARTICLE DENSITY ANALYSIS FOR THE H-2(1-SIGMA-G+) MOLECULE

Electron correlation in momentum space is assessed for the ground-stat e of H2 by examining changes in the two-particle probability density e valuated over preselected momentum planes. The associated radial and a ngular ''planar Coulomb shifts,'' DELTAR(p12) and DELTAA(epsilon(p)), are also calculated. This study complements an earlier analysis for H- 2 in position space. The natural expansion of the correlated wave func tion used previously was converted into momentum space by means of a D irac-Fourier transform. As before, correlation effects are measured wi th respect to the description provided by the first natural configurat ion. Characteristics of the three components of Coulomb correlation fo r a linear molecule are highlighted by specific choices for the moment um of a ''test'' or ''reference'' electron. Unlike position space, it was found that one component worked in distinct opposition to the othe r components, a feature analogous to atomic studies in momentum space. The trends observed throughout a series of probability changes in mom entum space for H-2 were rationalized and linked to the correlation be havior in position space.