Molecular Dynamics Simulation of the Thermodynamic and Structural Properties for the CaO-SiO₂ System

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The thermodynamic, structural and transport properties for the CaO-SiO₂ system were calculated by molecular dynamics (MD) simulation using the pairwise potential model with partial ionic charges. The interatomic potential parameters were determined by fitting the physicochemical properties of calcium oxide and calcium silicates with experimentally measured results. The calculated structural properties such as the pair distribution functions and the fractions of bonding types (bridging, non-bridging and free oxygen) of oxygen with silicon atoms in CaO-SiO₂ melts were in good agreement with observed results, and also the self-diffusion coefficients of calcium, silicon and oxygen ions have been calculated at 1 873 K. The ΔH^M, ΔS^M and ΔG^M for the CaO-SiO₂ system were calculated based on the thermodynamic and structural parameters obtained from MD simulation. The phase diagram for the CaO-SiO₂ system estimated by calculated Gibbs energy of mixing shows good agreement with observed result in the range above 50 mol% CaO and the liquid-liquid immiscibility region in the CaO-SiO₂ system have also been assessed by MD calculation.