{"ID":23681142,"CreatedAt":"2026-09-18T08:49:17.088671394Z","UpdatedAt":"2026-09-18T08:49:17.088671394Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2609.20645","arxiv_id":"2609.20645","title":"A Gaussian process coarse-grained potential for Na-montmorillonite","abstract":"Hydraulic transport in compacted bentonite is diffusion-controlled and governed by the hydration and microstructure of sodium montmorillonite (Na-MMT). Experiments cannot resolve how platelet interactions govern pore structure, transport and stiffness, while existing coarse-grained models smooth hydration oscillations or require manual corrections. We develop a tabulated potential combining Morse interactions between platelet centre and edge sites with a Gaussian process regression correction trained on all-atom potentials of mean force. It captures the hydration-induced complexity of the potential-of-mean-force profiles, including the three-water (3-W) hydration minimum and transfers across geometries, layer-charge variants and unseen configurations. Applied to monodisperse and polydisperse Na-MMT assemblies at dry densities of 0.8-1.3 g cm^-3, the model captures the 3-W to 1-W transition, loss of non-interlayer porosity and evolution of pore structure, random-walk tortuosity, diffusion and stiffness. Predicted diffusion agrees with compacted Na-bentonite measurements.","short_abstract":"Hydraulic transport in compacted bentonite is diffusion-controlled and governed by the hydration and microstructure of sodium montmorillonite (Na-MMT). Experiments cannot resolve how platelet interactions govern pore structure, transport and stiffness, while existing coarse-grained models smooth hydration oscillations...","url_abs":"https://arxiv.org/abs/2609.20645","url_pdf":"https://arxiv.org/pdf/2609.20645v1","authors":"[\"Yalda Pedram\",\"Yaoting Zhang\",\"Laurent Brochard\",\"Chang Seok Kim\",\"Laurent Karim Béland\"]","published":"2026-09-17T16:26:22Z","proceeding":"cond-mat.mtrl-sci","tasks":"[\"cond-mat.mtrl-sci\"]","methods":"[\"Diffusion Model\"]","has_code":false}