Many-Electron Theory of Atoms and Molecules. V. First-Row Atoms and Their Ions

Publisher Website
Google Scholar
Abstract
The correlation energies of the 1s22s2 inner cores of the first‐row atoms B, C, ···, Ne are found to be very different from those of the corresponding four‐electron Be‐like ions, B+ to Ne6+, due to the exclusion effects of the outer 2p electrons. Whereas the 2s2 correlation, ε(2s2), in the 1s22s2 ions increases from —1.13 eV in Be to —3.2 eV in Ne6+, the 2s2 correlation in the neutral atoms decreases from —1.13 eV in Be to —0.27 eV in Ne. The many‐electron theory was used for the nonempirical 2s2 calculations and included the use of the r12 coordinate. With these theoretical ε(2s2) values the correlation of a 2p electron with the 1s22s2 inner core is found to be large, ∼—1 eV. Also the 2p2 correlation comes out about —1 eV. The results show that core energies will, in general, depend strongly on the state and number of the outer‐shell electrons and that intershell correlation interactions may be appreciable. Implications for π‐electron systems and the ligand‐field theory of inorganic complexes are discussed.