Singlet and Triplet Bound State Spectra in the Four-Electron Be-Like Atomic Systems

Configuration Interaction Study of the 3 P Ground State of the Carbon Atom

“…The procedure of selection of the configurations is similar to that described in our previous works, Refs. [23,24].…”

“…For example, the configuration ppsspp is the product of ( 1 S pp) ( 1 S ss) ( 3 P pp). Other configurations not appearing in Table 1 have been already given in previous papers and are here omitted, see [20,23]. Table 1: Configuration terms needed for the construction of two-and three-electron configurations with M L =0.…”

“…First for a relatively short expansion the orbital exponents are optimized. We use the same technique than in previous calculations of the Be and Li atoms [20,23,24]. A set of three exponents is used (one for the K-shell, other for the electrons of the inner L-shell and other for the pair of outer electrons of the L-shell), and kept equal for all configurations.…”

“…The atomic Hamiltonian for a fixed nucleus written in Hylleraas coordinates, see Ref. [23], for a CI wave function reduces effectively to:…”

“…For example, the configuration ppsspp is the product of ( 1 S pp) ( 1 S ss) ( 3 P pp). Other configurations not appearing in Table 1 have been already given in previous papers and are here omitted, see [20,23].…”