Carbon is an important element of life. In spite of its importance, the physical, chemical, and biological behavior and the global carbon cycle of many of Earth's carbon-bearing systems have not been thoroughly investigated under extreme conditions. Recently, it was found that high pressure-high temperature polymorphs of carbon dioxide can exhibit a great diversity in intermolecular interaction, chemical bonding, and crystal structures. The study of the high P-T phase relations of carbon dioxide thus has significant implications for deep Earth processes.
However, there are existing discrepancies on the crystal structures and nature of chemical bonding concerning several high-pressure polymorphs.
In this presentation, results on theoretical studies using first-principles molecular dynamics, on the solid and liquid phases at high pressure-high temperature will be presented. It will be shown that the experimental disagreements in the interpretation of the local structure can be explained once thermal effect is considered. The structure, electronic properties and dissociation mechanism of molten carbon dioxide near lower mantle condition will be reported.