MOMENTUM STUDIES OF ELECTRON CORRELATION IN THE GROUND-STATE OF THE H-3(+) MOLECULE ION

The consequences of Coulomb correlation in the momentum space descript ion of H-3(+) is examined in depth. Such an appraisal complements a pr evious analysis in position space for this simplest of polyatomic syst ems. As before, the ground state of the equilateral triangular conform ation of H-3(+) is described by a wave function which recovers almost 99% of the correlation energy. The momentum representations of this wa ve function and a Hartree-Fock counterpart are obtained by using a Dir ac-Fourier transform. The correlation effects are assessed by evaluati ng the changes which occur in the one-and two-particle probability den sities over preselected momentum planes. The associated radial and ang ular partial planar Coulomb shifts are also calculated. In each instan ce, different regions of p-space can be sampled by giving a ''test'' o r ''reference'' electron one of several specific fixed momentum values . Comparisons are made with an earlier and similar study of the effect of electron correlation for the ground state of H-2. The correlation characteristics for H-3(+) are also compared, briefly, with those obta ined in p-space for the ground states of HeH+ and some simple isoelect ronic atomic ions. (C) 1998 American Institute of Physics. [S0021-9606 (98)02014-5].