AB-INITIO CALCULATIONS OF THE STRUCTURE AND PROPERTIES OF SELECTED STATES OF $C_{2}$ AND $C_{3}$

S. R. Langhoff: NRC Associate.Author Institution: NASA Ames Research Center NASAAb-initio SCF + CI calculations of the structure and properties of $C_{2}$ and $C_{3}$ are described. The calculations on $C_{2}$ utilized a large Slater basis, while those on $C_{3}$ used a double-zeta-plus-polarization Cartesian Gaussian basis set. Large scale CI calculations (10 000 to 15 000 spin-adapted configurations) were performed on the low-tying states of $^{1}\Sigma_{g}^{+}$ and $^{3}\Pi _{g,u}$ symmetries for $C_{2}$ and for the $^{1}\Sigma_{g}^{+}$ and $^{1}\pi_{g,u}$ symmetries for $C_{3}$. The sum of the squares of the electronic transition moments, $\Sigma|R_{e}|^{2}$, between the various states as a function of internuclear distance are reported. The application of these results to entry physics studies being conducted at NASA-Ames Research Center are also described