SCF and MC–SCF Study of CO₂ with bond angle variation

Abstract

Multiconfipuration ( M C ) S C F calculations are reported for COz for bond angles bctween 60" and 180'. The ground state configuration is found to be.. .5af46:lb:laf for small bending angles and.. -6 a~3 b j l b~l a~ for large bending angles, the change in ground state character occurring at a bond angle of about 1 0 0 O . The force constant for bending obtained from the MC-SCF function is about 8.0% lower than the corrcsponding S C F value, and in considerably better agreement with experiment.

Potential energy surfaces of carbon dioxide

“…Some previous calculations [4,30,31] did not explore the 4 -range at sufficiently small values for finding the bent minimum. A three-configuration MCSCF calculation [3] in which the 0-C-0 angle was varied from 60" to 180" missed the bent minimum because the C-0 distance was kept constant at the equilibrium value (1.162 A) of the linear species. Only Feller et al [29] and Xantheas et al [26] have previously reported the bent minimum.…”