采用基于第一性原理的从头计算分子动力学方法,模拟了在300,400,500,600和700℃5种温度下TiO2分子在GaN(0001)表面吸附的动力学过程,研究了吸附过程中系统能量、动力学轨迹、Mulliken 布居分析、表面成键电子密度分布(ELF)以及扩散系数等性质.结果表明,温度会影响 TiO2分子中两个 O 原子与 GaN 表面两个Ga 原子成键顺序；500℃时 O2—Ga3成键的时间最早,TiO2在 GaN(0001)表面吸附生长的速率最快.600℃下TiO2分子在物理吸附阶段的扩散系数比在500℃下扩大了接近100倍,500℃时 O—Ga1的局域电荷分布ELF值最大为0．750,说明500℃下 O—Ga1键共价性最强.由此可见,TiO2分子在 GaN(0001)吸附生长最佳温度是500℃.
The dynamics simulates of adsorption process of TiO2 molecule on GaN(0001)surfaces in 300,400, 500,600 and 700 ℃ temperature are studied by Ab initio molecular dynamics methods based on the first prici-ples.The energies of system,dynamic trajectories,the analysis of Mulliken populations,the surface bonding e-lectron density distributions (ELF)and diffusion coefficients in the adsorption process are calculated and dis-cussed.The results show that the bonding sequence of O and Ga atoms are different in the different tempera-ture.The time of O2-Ga3 formation is the earliest and the rate of TiO2 adsorption on GaN (0001)surface is the highest in 500 ℃.The diffusion coefficient of TiO2 molecule in the physical adsorption stage in 600 ℃ in close to 100 times than that of 500 ℃.And the local charge distribution of ELF(0.750)of O-Ga1 in 500 ℃ is the most. The covalent bond of O-Ga1 bond is the strongest in 500 ℃.So the optimal temperature of TiO2 adsorption on GaN (0001)is 500 ℃.
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