Nuclear Magnetic Shielding Constants for Several 2-, 3-, and 4-Electron Atoms and Ions

Nuclear magnetic shielding constants have been calculated for H—, He, Li+, Be++, Li, Be+, and Be using both open- and closed-configuration wave functions with optimized orbital exponents. The accuracy of the values reported is supported by the close agreement between the values obtained for He, σ=5.9856×10—5 and σ=5.9913×10—5, respectively, and that obtained by Hylleraas and Skavlem using the first five terms of the Hylleraas wave function, σ=5.9938×10—5.