Abstract An MO SCF theory for molecules has been developed starting from Slater's study of atomic shielding constants. Use of shielding “constants” which are functions of the nature of the shielded electron gives good total energies for a number of atomic species. The good agreement must mean negligible errors due to correlation and self-repulsion. To extend this treatment to molecules the relation F μν = ∂ E/∂ P μν is used. The procedure has been parametrized for H, C, N, O and F.