First-principles study of isomorphic ('Dual-Defect') substitution in kaolinite - He, Man-Chao (China University of Mining and Technology. State Key Laboratory for Geomechanics and Deep Underground Engineering) ; Zhao, Jian (China University of Mining and Technology. State Key Laboratory for Geomechanics and Deep Underground Engineering) ; Fang, Zhi-Jie (China University of Mining and Technology. State Key Laboratory for Geomechanics and Deep Underground Engineering) ; Zhang, Ping (Institute of Applied Physics and Computational Mathematics)