Vibrations in (CO2)2: A correlated ab initio computational study

Abstract Vibrations of the carbon dioxide dimers are computed ab initio in the second order Moller-Plesset (MP2) perturbation treatment with the 6–31 + G* basis set. The calculations represent further support for the C 2 h isomer as local minimum and the C 2 v structure as an activated complex. In five cases the intra-molecular frequencies in the C 2 h dimer are increased compared to the related term of the monomer. The three most intense intra-molecular frequencies exhibit substantial shifts. Those predictions can be useful for preparations of further observations, for example in the atmosphere of Venus.