High-pressure melting behaviors of calcite from first-principles simulation

Calcite is a widely distributed and highly significant mineral on Earth. Understanding the physical properties and melting behavior of calcite facilitates the study of global carbon cycling, mantle dynamics, geological processes, and the structure and evolution of Earth and Earth -like planets. The existing experimental and theoretical data regarding calcite are not entirely consistent, and there is a lack of high-pressure melting data. Employing firstprinciples molecular dynamics (FPMD) combined with the Z method, we study the melting behavior of calcite at high pressures, determining the melting temperature up to 370 GPa. Through mean square displacement (MSD), radial distribution function (RDF), coordination number (CN), and diffusion coefficient (D), the melting temperature of calcite was established, enabling further exploration of its microscopic structural characteristics. The shock melting temperatures of PANDA and ANEOS models are lower than our FPMD melting curves. Compared with two -stage light gas gun experiments, the shock melting temperature is in good agreement, but the melting curve is different from static high-pressure experiment and laser shock experiment. The calcite melting curve exceeds the mantle melting curve, suggesting that the calcium -dominated carbonate system does not undergo melting throughout the entire mantle.