Phase transitions and phase diagram of silicon carbide at exoplanetary core conditions

High pressure high temperature behavior of crystalline SiC is being actively investigated with the goal of delivering key data for developing interior models of carbon-rich exoplanets. Recent static and dynamic compression experiments uncovered substantial differences in transition pressure from ambient zinc blende (or hexagonal) to high pressure rocksalt phases. The melting curves of both ambient and high-pressure phases are also poorly constrained. To bridge this knowledge gap, quantum molecular dynamics (QMD) simulations of the SiC phase diagram and shock Hugoniots are performed within a broad range of pressures (up to 1 TPa) and temperatures (up to 50,000 K). The QMD results reconcile the puzzling difference between the static and dynamic shock compression experiments while delivering accurate equation of state of the solid and liquid phases as well as the SiC melting lines. The QMD simulations are in good agreement with recent dynamic compression experiments.