Molecular dynamics calculations have been used to explore the structure and dynamics of clusters of carbon dioxide, ranging in size up to 164 molecules. The most detailed calculations have been carried out around T=90 K with a view to interpreting the results of infrared data on clusters produced in a seeded argon beam. Under appropriate conditions, in addition to liquid‐like clusters, we have been able to produce clusters with the following structures: (i) an ordered solid—analogous to the bulk crystal, (ii) a bulk–solid core with liquid‐like outer layers, (iii) an amorphous solid, and (iv) an amorphous solid core with liquid‐like outer layers. We have calculated the dispersion of the infrared active intramolecular Q3 mode for these clusters using the transition‐dipole transition‐dipole interaction that is usually invoked to explain the infrared spectrum of the bulk crystal. The resulting spectrum for the Q3 mode of each type of cluster is quite distinct in appearance. This observation suggests that molecular dynamics calculations could be a valuable diagnostic tool in the study of clusters. The dynamical behavior of these clusters has also been investigated, and we find evidence for the existence of large‐amplitude, low‐frequency symmetric breathing modes with frequencies in the range 2–4 cm−1. The overall shape of the experimental Fourier transform infrared spectra of clusters produced in a seeded argon jet is very similar in appearance to the calculated spectrum for a cluster of 116 molecules with an ordered solid core and liquid‐like outer layers.
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