High-pressure molecular phases of solid carbon dioxide

TL;DR

This study uses first-principles calculations to analyze solid carbon dioxide under high pressure and temperature, proposing molecular structures that align well with experimental data, challenging previous interpretations of intermediate phases.

Contribution

It offers a new theoretical perspective on CO2 phases, replacing the idea of intermediate states with molecular structures consistent with experimental observations.

Findings

Molecular structures of CO2 are consistent with experimental data.

Reevaluation of the intermediate phase concept in CO2.

First-principles calculations support molecular phase stability.

Abstract

We present a theoretical study of solid carbon dioxide up to 50GPa and 1500K using first-principles calculations. In this pressure-temperature range, interpretations of recent experiments have suggested the existence of CO2 phases which are intermediate between molecular and covalent-bonded solids. We reexamine the concept of intermediate phases in the CO2 phase diagram and propose instead molecular structures, which provide an excellent agreement with measurements.