The problem of localization of atomic and molecular electron momentum is investigated. The atomic systems are studied in terms of the electron momentum localization function (EMLF), a momentum-space counterpart of the electron localization function introduced by Becke and Edgecombe [J. Chem. Phys. 92, 5397 (1992)]. The shell structure of atoms is better represented by the EMLF than the corresponding radial momentum density and Laplacian of the electron momentum density (EMD). A clear distinction is possible for monotonic and nonmonotonic decreasing atomic EMD’s from the EMLF plots. For molecules, the localization is studied via both the Laplacian and the EMLF and are found to be in agreement with each other. The critical structure of the EMD at p=0 is represented by the corresponding concentrations and depletions in the Laplacian contour plot.

• Received 10 February 1994

DOI:https://doi.org/10.1103/PhysRevA.50.2202