Calculation of the Electronic Structure of Atoms and Molecules.

The report covers the first year of a continuing program to develop practical computational methods for calculating the electronic structure of atoms and molecules. Programs have been written and tested on 4- and 6- electron systems for calculating the second-order generalized density operator gdo of any atom. Knowledge of this second-order gdo is exactly equivalent to knowing the full wave function for any one- or two-electron observable. With a very limited set of basis functions 4s and 2p orbitals 70 of the correlation energy of Be has been recovered. Furthermore, a major simplification in the N-fermion representability conditions derived earlier has been obtained. Author