Intracule functional models

1926 marked the beginning of a radically new chapter in the history of chemistry, for the advent of the Schrödinger equation finally transformed chemistry into a calculable science. The problem, of course, was the inordinate complexity of the equation for all but the simplest of atomic and molecular systems and the discipline of Quantum Chemistry may be usefully characterised as the development and application of methods for reducing that complexity to tractable levels. Soon after Schrödinger’s seminal publications, Hartree recognized that most of the difficulties associated with the Schrödinger equation for a general many-electron system can be avoided if its wavefunction is approximated by a product