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.



Research Center/Lab(s)

Center for High Performance Computing Research


The authors are thankful for the support from the Canadian Natural Sciences and Engineering Research Council. Richard Dawes and Ernesto Quintas-Sánchez are supported by the U.S. National Science Foundation (Grant No. CHE-1566246).

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)

0021-9606; 1089-7690

Document Type

Article - Journal

Document Version

Final Version

File Type





© 2019 The Authors, All rights reserved.

Publication Date

01 Aug 2019

PubMed ID


Included in

Chemistry Commons