Electron-pair densities of singly charged atoms in momentum space

Abstract

Spherically averaged electron-pair relative-motion (intracule) and centre-of-mass-motion (extracule) densities in momentum space are constructed and examined systematically for the 53 singly charged cations from Li+ to Cs+ and 43 stable anions from H- to I- in their ground states, based on numerical Hartree-Fock calculations. The intracule and extracule densities are found to be classified into three and two types, respectively, according to the number of extrema and their locations. The modalities of the electron-pair densities for all the 96 ions are governed by a few outermost electron pairs as reported for neutral atoms. The intracule and extracule moments as well as the electron-electron coalescence and counterbalance densities are computed for the 96 ions and compared with the corresponding values for the isoelectronic neutral atoms.