A density functional theory study of the alkali metal atom–carbon monoxide interactions: Singularity of the Li atom.

The LiCO molecule has been previously characterized experimentally in rare gas matrices by a large red shift of the CO stretching mode and a Li–C vibration around 600 cm-1 indicating a relatively strong Li–C bonding. Up to now, post Hartree–Fock ab initio methods had described this complex as unstable in its electronic ground state and predicted a linear metastable structure owing to strong induction forces between this complex and the surrounding polarizable rare gas atoms. Electronic and vibrational calculations at the harmonic approximation on this molecule using approximate density functional theory give results which are better in line with the experimental results. Two distinct bounded structures are found to be stable in the electronic ground state for the LiCO complex. The credibility of these calculations is also assessed in two ways; the first one is the comparison between experimental and calculated vibrational analysis on the νCO modes of the Li(CO)n (n=2,3) complexes. The second one is the study of the eventual complexation of Na and K atoms with the CO molecule and the comparison with experimental available data. © 1995 American Institute of Physics. [ABSTRACT FROM AUTHOR]