ELECTRONIC STRUCTURE OF GROUND AND SOME LOW-LYING EXCITED STATES OF CoCO: AN AB INITIO MOLECULAR ORBITAL STUDY

$^{a}$Hikida, et al.: two papers submitted to the session for Radicals and Ions of this 57th Symposium (2002).Author Institution: Department of Chemistry, Faculty of Science, Kyushu University; Department of Chemistry, Faculty of Science, Ochanomizu University; Tsukuba Advanced Computing Center, National Institute of Advanced Industrial Science and TechnologyMR-SDCI + Q and MR-ACPF molecular orbital calculations with the Roos-ANO basis sets have been carried out for the ground and some low-lying excited states of CoCO in order to determine the molecular constants and electronic structures, which will be comprehensive to those from the IR and millimeter-wave spectroscopies.$^{a}$ Dynamical electron correlations for the $8-10\sigma$ electrons are taking into account in the MR-SDCI + Q calculations with the active space consisting of Co 3d, 4s orbitals and $CO \pi, \pi^{\ast}$ orbitals. Relativistic energy corrections and spin-orbit interaction were also calculated. The electronic ground state was confirmed to be ${^{2}}\Delta_{i}$, and calculated rotational constant and vibrational frequencies agreed well with experimental values. Dipole moment and spin-orbit coupling constant were predicted to be 3.8 D and $-486 cm^{-1}$, respectively. Energy levels and electronic structure of some low-lying excited states have also been calculated