Spurious center of mass effects in a dynamically determined basis

A practical method for reducing spurious center of mass (CM) effects in a dynamically determined basis is reviewed and demonstrated for two solutions of the Hartree-Fock (HF) equations for 16O. The HF ground state (lower intrinsic energy) is mixed in parity and angular momentum and has higher CM energy than the spherically symmetric solution of good parity. Projection after variation, followed by diagonalization of a CM hamiltonian in this two state sub-space to eliminate spurious excitations of the CM, produces a state with 250 keV lower intrinsic energy than just projection after variation of the HF ground states. (orig.)