Molecular structures of CO$_{2}$ and N$_{2}$O under pressure

Carbon dioxide and nitrous oxide are investigated at pressures up to 50 GPa and 1000 K using \textit{ab initio} methods. In this pressure-temperature range, both materials have a number of stable molecular structures. We demonstrate that the constituent molecules in these structures do not undergo significant changes and that the proposed phases are consistent with experimental data. The differences found between the CO$_{2}$ and N$_{2}$O phase diagrams can be understood in terms of the polarity of the N$_{2}$O molecules.