GaN(0001)表面吸附TiO_2的DFT研究

Density-functional Pseudopotential Study of TiO_2 Adsorption on GaN(0001) Surface

建立了GaN(0001)2×2表面吸附模型,采用基于DFT动力学赝势方法,对TiO2分子的吸附进行了理论计算.研究了TiO2分子在GaN(0001)表面的吸附成键过程、成键方位及表面化学键特性.计算结果表明吸附过程经历了物理吸附、化学吸附与稳定态形成的过程,化学结合能达到7.184～7.423 eV.不同初始位置的TiO2分子吸附后,Ti在fcc或hcp位置,两个O原子分别与表面两个Ga原子成键,Ga—O化学键表现出共价键特征,O—O连线与GaN[11-20]方向平行,与实验观测(100)[001]TiO2//(0001)[11-20]GaN一致.

The bonding process,bonding orientation and bonding characteristics of TiO2 adsorption on GaN（0001）2×2 surface are investigated by use of pseudopotentials in molecular-dynamical density-functional theory.The results reveal three distinct stages： phys-sorption,chem-sorption and stable state formation of TiO2 on GaN（0001） substrate.The chemical bonding energy comes up to 7.184～7.423 eV.Ti atom in different initial position is adsorbed on fcc site or on hcp site,and two O atoms are combined with two Ga atoms on GaN surfaces after adsorption.The chemical bonding of Ga—O shows a covalent feature.The O—O line direction is paraller to the GaN direction in accordance with experimental reports of（100） TiO2//（0001）GaN.