氧分子在镍钛合金(100)表面吸附行为的研究

NiTi形状记忆合金作为一种广泛使用的生物医学材料，表面形成的氧化膜是其具有良好生物相容性的基础。氧分子在NiTi合金表面的吸附是其形成氧化膜的关键，应用离散变分Xα方法，首次对O2分子在B2结构NiTi(100)表面的吸附过程进行了理论研究，分别计算了在两种不同的O2分子吸附方式中Ti-O原子间的键级和电荷分布。结果表明：O2分子垂直接近NiTi(100)表面对其发生吸附更为有利。在吸附过程中，O2分子中只有一个氧原子被其最近邻的一个表面铁原子所吸附，而合金中其它表面原子及体相原子的电子结构没有变化。Mulliken集居数及局域态密度分析表明，吸附过程中铁原子与氧原子之间的相互作用主要是由2p(O)电子和4s，4p(Ti)电子贡献。

The study of Oxygen adsorption behavior on NiTi (100) surface

NiTi shape memory alloy is widely used as a biomaterial for the good compatibilities of its surface titanium oxide. Oxygen adsorption on NiTi surface is important for the formation of titanium oxide, the discrete variational Xa method(DV- Xa ) within the framework of density-functional theory is applied to study O2 molecule adsorption process on NiTi(100) surface. The bond order and charge distribution between Ti atom and O atom for two possible O3 molecule adsorption ways on NiTi (100) surface is calculated it is found that the adsorption way for O - O bond perpendicular to NiTi( 100) surface more preferred than that for O - O bond parallel to NiTi( 100) surface. O2 molecule only interacts with the nearest surface titanium atom from it during the adsorption process. The electronic structure of the other surface atoms and bulk atoms are not altered. Mulliken population and partial density of state analysis show that the interaction between Ti atom and O atom is mainly donated by the 2p (O) electrons and the 4s, 4p(Ti) electrons during the adsorption process.