An accurate ab initio ground-state intermolecular potential energy surface (PES) was determined for the CO-CO2 van der Waals dimer. The Lanczos algorithm was used to compute rovibrational energies on this PES. For both the C-in and O-in T-shaped isomers, the fundamental transition frequencies agree well with previous experimental results. We confirm that the in-plane states previously observed are geared states. In addition, we have computed and assigned many other vibrational states. The rotational constants we determine from J = 1 energy levels agree well with their experimental counterparts. Planar and out-of-plane cuts of some of the wavefunctions we compute are quite different, indicating strong coupling between the bend and torsional modes. Because the stable isomers are T-shaped, vibration along the out-of-plane coordinates is very floppy. In CO-CO2, when the molecule is out-of-plane, interconversion of the isomers is possible, but the barrier height is higher than the in-plane geared barrier height.
E. Castro-Juarez et al., "Computational Study of the Ro-Vibrational Spectrum of CO-CO₂," Journal of Chemical Physics, vol. 151, no. 8, American Institute of Physics (AIP), Aug 2019.
The definitive version is available at https://doi.org/10.1063/1.5119762
Keywords and Phrases
Carbon dioxide; Dimers; Ground state; Potential energy; Quantum chemistry; Van der Waals forces, Computational studies; Intermolecular potential energy surfaces; Lanczos algorithm; Ro-vibrational energies; Rotational constants; Transition frequencies; Van der Waals dimer; Vibrational state, Isomers
International Standard Serial Number (ISSN)
Article - Journal
© 2019 The Authors, All rights reserved.
01 Aug 2019