Knowledge Bank

Correlated potential energy and dipole moment curves are reported for the $X1\Sigma +,a 3\pi ,A1\Sigma +$, and $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Sigma +$ states of CaO over the range 3 a.u. $\le R\le 6$ a.u. Vertical and adiabatic energy levels, spectroscopic constants, curve crossings, and dipole moments are determined using the calculated curves and Field’s $analysis.1$ The calculations are the first calculations which correctly predict that $X1\Sigma +$ is the ground state, and the calculated results for $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}\Sigma +$ are the first accurate values available. Analysis of the calculated results provides a simple interpretation of valence electron correlation in CaO. Core electron behavior is apparently more complicated. It appears that either explicit core correlation and/or relativistic correlations are necessary in Ca and K containing ionic compounds.