第一性原理研究H_2O分子在CaCO_3(104)表面吸附  

First principles study on the adsorption of H_2O molecule on CaCO_3(104) surface

作　　者：柴汝宽 刘月田 王俊强 辛晶 皮建 李长勇 CHAI Ru-Kuan;LIU Yue-Tian;WANG Jun-Qiang;XIN Jing;PI Jian;LI Chang-Yong(State key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing 102249,China;Development Research Dep.,CNOOC Research Institute,Beijing 10028,China)

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中海油研究总院开发研究院,北京100028

出　　处：《原子与分子物理学报》2018年第6期1075-1082,共8页Journal of Atomic and Molecular Physics

基　　金：国家科技重大专项(2017ZX05032004-002);国家重点基础研究发展计划(973计划)(2015CB250905);中国石油重大科技专项(2017E-0405)

摘　　要：基于密度泛函理论的第一性原理方法模拟研究H_2O在CaCO_3(104)表面的吸附特征.首先,研究H_2O分子在CaCO_3(104)表面的顶位、桥位(短桥位、长桥位)和穴位上垂直和平行表面两种类型下的8种高对称吸附结构模型,结合吸附能和稳定吸附构象确定最优吸附位.而后,基于H_2O/CaCO_3(104)最优吸附结构模型,研究吸附前后H_2O和CaCO_3(104)表面的物理结构、电子结构(Mulliken电荷布居数、态密度、电子局域函数)的特征,分析H_2O/CaCO_3(104)表面之间的相互作用以及成键机理.研究结果:吸附能和体系稳定构象显示H_2O分子/CaCO_3(104)表面的最稳定吸附结构为穴位-平行.在穴位-平行位吸附后,H_2O分子的O-H键长和H-O-H键角均发生改变; CaCO_3晶体平行和垂直(104)表面方向上原子位置均发生改变,表面层变化最大;即吸附作用对H_2O分子和CaCO_3晶体的物理结构均产生较大影响; H_2O/CaCO3(104)最优吸附体系的Mulliken电荷布居数、电子态密度、电子局域函数的研究均说明H_2O分子与CaCO3(104)之间存在电子的转移形成化学键.其中,Ca-O(H_2O)形成离子键,H(H_2O)-O(CaCO_3)之间存在氢键作用.本文研究揭示了方解石表面水湿性的原因,同时为方解石润湿性的深入研究奠定基础.The adsorption characteristics of H2O on CaCO3(104)surface were studied by the first principle.Firstly,we studied8high symmetry adsorption structural models of H2O molecules on the top position,bridge position(short bridge position,long bridge position)and hollow position of the CaCO3(104)surface,respectively,with vertical or parallel to surfaces.Combined with adsorption energy and stable adsorption conformation,the optimal adsorption site was determined.Then,based on the H2O/CaCO3(104)optimal adsorption structure model,we studied the variation of the physical structure and the electron structure(Mulliken population analysis,Density of state,Electron localization function)of the H2O/CaCO3(104)system.Based on these we analyzed the interaction between H2O/CaCO3(104)surface.Results showed that the most stable adsorption structure is hollow-parallel.After H2O adsorbed on CaCO3(104)surface,the O-H bond length and the H-O-H bond angle of H2O molecules were all changed,and the atomic positions of CaCO3(104)crystals in the directions of parallel and vertical to(104)surface were also all changed,in which atoms of the surface layer changed most.That is,the adsorption has great influence on the physical structure of H2O and CaCO3crystals.Study on the Mulliken population analysis,the density of state and the electron localization function of the H2O/CaCO3(104)system showed that there exist electron transfer between H2O molecule and CaCO3(104)and chemical bond were formed.Ca-O(H2O)is ionic bond and H(H2O)-O(CaCO3)is hydrogen bond.This study reveals the mechanism of water-wet calcite surface and lays the foundation for further research on the wettability change.

关 键 词：第一性原理 CaCO3(104)表面 H2O分子 吸附特征 

分 类 号：O641[理学—物理化学]