Ab initio thermodynamic model for magnesium carbonates and hydrates

Area of Science:

• Geochemistry and Mineral Physics
• Computational Materials Science

Background:

• Predicting thermodynamic properties of hydrated magnesium carbonate minerals is crucial for understanding geological processes and material synthesis.
• Existing models often lack accuracy or broad applicability across diverse experimental and geological conditions.

Purpose of the Study:

• To develop an ab initio thermodynamic framework for predicting the properties of hydrated magnesium carbonate minerals.
• To establish a reliable computational tool for exploring mineral formation pathways and transformations.

Main Methods:

• Utilized density-functional theory (DFT) combined with macroscopic thermodynamics.
• Incorporated experimental chemical potentials for MgO, water, and CO2.
• Applied Grimme's semiempirical dispersion corrections and Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation with heat of formation corrections.

Main Results:

• Achieved quantitative agreement for benchmark minerals: brucite, magnesite, nesquehonite, and hydromagnesite.
• Demonstrated the model's ability to predict mineral outcomes based on experimental conditions (e.g., nesquehonite, hydromagnesite, magnesite formation).
• Showcased extensibility to predict properties of unobserved minerals and evaluate thermodynamic data for known ones.

Conclusions:

• The developed ab initio thermodynamic framework provides a reliable and extensible tool for studying hydrated magnesium carbonates.
• The model accurately predicts mineral stability, formation pathways, and transformations under various conditions.
• This approach enables exploration of mineral properties beyond current experimental accessibility, including defective or transitional structures.