Ab initio calculation of atomic structure and mechanical property of kaolinite under different temperatures

Kaolinite, a predominant and widely distributed clay mineral, finds extensive applications in construction, industry, and agriculture, which rely on its physical, chemical, and mechanical properties.This study employed quantum mechanics-based first-principles calculations to investigate the crystal structure, electronic properties, and mechanical properties of kaolinite at different temperatures from a microscopic perspective.Main conclusions are as follows: Structurally, lattice parameters (a, b, c) and volume V increased with temperature, with c showing the largest increment.The interlayer spacing between silicate tetrahedral and alumina octahedral layers slightly decreased from 0.3733 to 0.3702 , indicating temperature exerts a greater effect on interlayer hydrogen bonds.Electronically, in 0-750 K, kaolinite's band gap narrowed from 5.13 eV to 5.06 eV; s-orbital electrons of Al atoms jumped from valence to conduction band, reducing insulation.Mechanically, elastic constants C 11 , C 22 , C 33 , C 44 , C 66 decreased while C 55 increased with temperature.Bulk modulus declined continuously, whereas shear modulus and Young's modulus first rose then fell.The universal