VARIATIONAL BOUNDS IN DIRAC-FOCK BASIS SET EXPANSION CALCULATIONS

Energy bound properties of two recently proposed Dirac-Fock basis set expansion schemes are examined in calculations on several highly ionized as well as neutral atom species. Both schemes employ expansions in Gaussian-type functions, and both model the nucleus as a sphere of uniformly distributed positive charge, but they differ in the manner in which spinors of k > 0 symmetries are expanded in the basis. The 2p 1 2 states of C5+ and Hg79+, the J=0 (2p 1 2)2 states of the carbon and the ground state of the neutral Hg atom were studied. Bounds failures are observed in those calculations on highly ionized species in which a "contracted" expansion for k > 0 spinors is used. Advantages and disadvantages of the two methods are discussed. © 1990.