A new many-body potential energy function is developed for reproducing the potential energy surface (PES) of carbon dioxide (CO2) systems with flexible monomers. This function is generated by fitting the electronic energies of CO2 monomers and dimers at the CCSD(T)-F12/aug-cc-pVTZ level of theory and basis set. In total, over 300,000 configurations of CO2 were used to train the potential function. Comparisons of the PESs of 6 orientations of CO2 dimers at carbon-carbon distances ranging from 2 – 8 angstroms were performed to demonstrate the accuracy of the methodology. The largest difference between the model and reference energies was less than 10 cm-1. Further, the potential function was used to determine the minimum energy structures of CO2 clusters ranging in size from 3 – 13 molecules. A separate potential function was fit to MP2 reference energies and was directly compared to clusters optimized at the full MP2/aug-cc-pVDZ level of theory. The cluster geometries and energies obtained with the CCSD(T)-F12 potential function are shown to be in very good agreement with experimental results.

Development of a many-body carbon dioxide potential and its application to clusters up to (CO2)13

253rd National Meeting (2017)

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