Classical trajectory study on an ab initio CI vibrotor potential energy surface for Li+-CO differential cross sections

A previous rigid rotor potential surface for Li⁺-CO has been improved by computing surface points for two additional CO bond lengths at three different angles of orientation. The CI calculations including all single and double excitations which can be generated within the Hartree-Fock SCF molecular orbital basis have been improved by taking certain quadruple excitations into account in an approximate way. Classical trajectories computed on this surface have been used to determine differential cross sections at scattering angles of 37.1°, 43.2° and 49.2°, and for a relative kinetic energy of 4.23 eV. Comparison with experiment shows that inclusion of CO vibrations does not account for the discrepancy found previously between the classical rigid rotor and the experimental results. When summed over all final vibrational levels the vibrotor results are nearly identical to the rigid rotor cross sections.