Knowledge Bank

In spite of the long range of the coulomb repulsions between electrons, the nuclear wells and exclusion principle are responsible for the shell structure of atoms and molecules. Orbital pictures are qualitatively successful though correlation errors are as large as molecular binding energies. The physical basis of our theory which builds an atom or molecule from electrons correlating only in pairs in a Hartree-Fock “sea” will be discussed. In contrast to a free electron gas, in atoms and molecules many electron correlations are unimportant. Specific cases such as Boron will be discussed. The theory justifies the semi-empirical H-electron theories and also makes it possible to calculate the electronic properties of quite large, atoms and molecules to high accuracy as in He and $H2$ and in similar ways.