Chemical Physics Letters, Vol.340, No.5-6, 547-551, 2001
On the extremum property of electron density functions in position and momentum spaces
For statistically uncorrelated wave functions, the electron density p(r) is known to be an extremum function of the generalized electron-pair density g(q; a, b), which smoothly connects p(r), the electron-pair intracule (relative motion) density h(u), and the electron-pair extracule (center-of-mass motion) density d(R). The present systematic examination of the numerical Hartree-Fock results of moments (r(n)), (u(n)), (R-n) and density values at the origin p(0), h(0), d(0) for 102 neutral atoms and 96 singly charged ions suggests that p(u) is Focal maximum for a small q and is local minimum for a large q of the function g(q; a, b). Analogous results ar e obtained for the momentum-space counterparts Pi (p) and (g) over bar (t; a, b).