ABSTRACT
The discussion of atoms and molecules by physicists and chemists until the 1920s, was limited to position space. Exploration of these systems in momentum space began with the pioneering work [1] of Pauling and Podolsky in 1929, in which they applied a Fourier-Dirac transformation [2], as given by Jordan in 1927, to the hydrogenic orbitals. The aim of this was to obtain the wave function in momentum space and thereby the probability of an electron having momentum in a given range. This was related to the experimental Compton line shapes giving electron momentum densities (EMDs) for an atomic system [3]. It was shown by Pauling and Podolsky [1] that the orbitals in position space transformed to momentum space yield the familiar associated Legendre functions Pml (cos u) multiplied by e
imf. In momentum space, the radial part was described by a Gegenbauer polynomial instead of the Laguerre polynomial in position space [1].
