Programme

O.48 -- Oral, VCTP-51

Date: Thursday, 6 August 2026

Time: 16:40 - 17:00

Pressure-Dependent Structural and Mechanical Properties of Kaolin Group Minerals: A First-Principles and Molecular Simulation Study

Nguyen Minh Phi (1), Brahim-Khalil Benazzouz(2), Tran Thi Thu Hanh(3), Ho Khac Hieu(4), Guillaume Galliero(5), Hoang Hai(1)

(1) Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City, Vietnam; (2)Laboratory of Civil Engineering and Environment Materials, Ecole Nationale Polytechnique, Algiers, Algeria; (3) Ho Chi Minh City University of Technology, VNU-HCM, Ho Chi Minh City, Vietnam; (4) Faculty of Physics and Chemistry, University of Da Nang - University of Science and Education; (5) Laboratoire des Fluides Complexes et leurs Réservoirs, Université de Pau et des Pays de l’Adour, E2S UPPA, CNRS, Pau, France

[Abstract] Kaolin-group clay minerals, including kaolinite, dickite, and nacrite, are important constituents of clay-rich geological formations and may be relevant to the mechanical integrity of caprocks used for underground H2 and CO2 storage [1]. However, their pressure-dependent structural and mechanical properties remain poorly constrained because experimental determination is still challenging. This study aims to address this limitation by combining two complementary computational approaches: first-principles density functional theory and classical atomistic simulations. Density functional theory calculations were performed using CASTEP [2]. The calculations employed the PBE generalized-gradient approximation, ultrasoft pseudopotentials, a plane-wave cutoff energy of 1000 eV, and Monkhorst–Pack k-point meshes selected to ensure total-energy convergence. Long-range dispersion interactions were accounted for using the D3 correction. Classical atomistic simulations were conducted using the General Utility Lattice Program (GULP) [3], in which interatomic interactions were described by Coulomb, Buckingham, Morse, harmonic bond-bending, and core–shell potentials. Polytype-specific potential parameters were obtained through relaxed fitting to experimental structural data. The results from both approaches are compared with available experimental and computational data to evaluate the reliability of the predicted pressure dependence of structural and mechanical properties of Kaolin group clays. This combined analysis provides molecular-scale insight into polytype-dependent layer stacking and interlayer interactions in controlling the structural and mechanical responses under static pressure. [Acknowledgements] The authors gratefully acknowledge the support of the Vietnam National Foundation for Science and Technology Development (NAFOSTED) under grant number 103.01-2025.42. Computational resources were provided by the University of Pau and Pays de l’Adour (UPPA) and the MCIA (Mésocentre de Calcul Intensif Aquitain). [References] [1] S. R. Thiyagarajan, H. Emadi, A. Hussain, D. M. Fernandez, I. Ispas, S. K. Henderson, and M. Watson, J. Energy Storage 171, 123007 (2026). [2] S. J. Clark, M. D. Segall, C. J. Pickard, P. J. Hasnip, M. J. Probert, K. Refson, and M. C. Payne, Z. Kristallogr. 220, 567–570 (2005). [3] J. D. Gale and A. L. Rohl, Mol. Simul. 29, 291–341 (2003).

Presenter: Nguyen Minh Phi