Molecular dynamics studies of the structural and transport properties of CaO-Al2O3-SiO2 melts: Comparing the accuracy of the empirical force fields

H Verbeeck and I Bellemans and D Lamoen and N Moelans, COMPUTATIONAL MATERIALS SCIENCE, 259, 114150 (2025).

DOI: 10.1016/j.commatsci.2025.114150

Empirical force fields are widely used in classical molecular dynamics (MD) simulations to model the structure and dynamics of oxide melts such as CaO-Al2O3-SiO2, a system of significant industrial relevance. However, a systematic benchmarking of the most commonly used force fields for this ternary system to assess their transferability and accuracy in the molten state has not yet been presented in the literature. As such, this study analyses both the structural properties, such as density, bond lengths, and coordination numbers, and the dynamic properties, such as self-diffusion coefficients and electrical conductivity, of CaO-Al2O3-SiO2 melts across ten compositions and five temperatures ranging from 1400 to 1600 degrees C. The performance of the force fields proposed by Matsui, Guillot, and Bouhadja is evaluated by comparing classical MD predictions with experimental data, CALPHAD-based density models, and ab initio molecular dynamics (AIMD) simulations. While Matsui's and Guillot's force fields accurately reproduce densities and Si-O tetrahedral environments, Bouhadja's force field shows better agreement with AIMD predictions for Al-O and Ca-O bonding. Regarding dynamic properties, Bouhadja's force field yields the best agreement with experimental activation energies and demonstrates robust transferability beyond its original parameterization range. This benchmark study is the first to comprehensively validate these force fields for both structural and transport properties in the molten phase, and identifies Bouhadja's potential as the most physically accurate and reliable choice for simulating transport phenomena in CaO-Al2O3-SiO2 melts.

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