Local-density-functional model for atoms in momentum space

A local-density-functional model in momentum space enabling direct calculations of electron momentum densities for atomic systems is presented. This is based on the coordinate-space local-density-functional model of Parr et al. in conjunction with quasiclassical phase-space considerations. Within the model, electron-electron interaction and nuclear-electron attraction energies turn out to be simple local functionals of momentum density while kinetic energy has been treated exactly. The momentum densities obtained through this model have a simple algebraic form. Numerical investigations employing these densities reveal that reasonable estimates of various $〈p^n〉$ expectation values as compared to their Hartree-Fock counterparts can be obtained.