A Gibbs Thermodynamic Surface Approach to Modeling the Melting of Forsterite

The process of melting is widespread in nature and plays a crucial role in the evolution of magma oceans on Earth and other planetary bodies. Given that planetary interiors are generally subjected to high-pressure conditions, the study of melting behavior under high-pressure conditions is essential for understanding the composition and dynamic evolution of planetary interiors. Based on the theory of the Gibbs thermodynamic surface and previous research, this study employs ab initio molecular dynamics simulation combined with a geometric model to obtain the melting data of forsterite (Mg₂SiO₄) within the pressure range of 0 to 16 GPa. Under limited computational resources, this method enables the efficient and accurate acquisition of melting-related properties at any point within a given pressure range, including the Gibbs free energy, Helmholtz free energy, enthalpy, internal energy, entropy, and volume of solid and liquid phases. This approach is also used to determine the phase boundary between forsterite and wadsleyite within the temperature range of 1200 to 1500 K. The calculated results show high consistency with existing experimental and computational data, validating the reliability and accuracy of this method for obtaining melting data under high pressure. This approach overcomes the bottleneck of existing methods in efficiently obtaining complete high-pressure melting data with limited computational resources.