Electronic Wave Functions for Atoms. IV. Ground State of Ne

The configuration-interaction (CI) method is employed in an exhaustive investigation of the ground state of Ne. A 231-term CI expansion (formed from a determinantal space of dimension 5343), obtained with an optimized $6s6p5d4f$ basis, gives an energy E=-128.8868 a.u. (Ne). The Ne wave function is compared with those of Ne⁶⁺ and Ne⁸⁺. A quantitative assessment of all sources of truncation errors is given. The nonrelativistic energy is estimated to be -128.932±{}0.008 a.u. (Ne), in agreement with previous estimates obtained by different methods. Three- and four-excited determinants are shown to contribute 1% of the correlation energy. The L-shell correlations are shown to be nonadditive. Also, about 8% of the correlation energy is given by configurations containing g, h, and higher harmonics.