NiTi形状记忆合金是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。大量实验表明氧分子在NiTi合金表面的吸附是其形成氧化膜的关键。本文采用密度泛函方法应用赝势基组对NiTi合金（100）表面的电子结构以及氧分子的吸附和解离过程进行了系统研究。结果表明，Ti原子裸露表面比Ni原子裸露表面反应活性高，O2吸附为活化解离吸附，顶位吸附结构最不稳定，易向桥位或洞位吸附转化，桥位吸附对应的吸附结构最为稳定。态密度分析和结构分析表明，O原子与表面的相互作用主要是由O原子价轨道和NiTi合金杂化表面轨道贡献。
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. In this work, first principle pseudopotential plane wave calculations based on density functional theory and the generalized gradient approximation (GGA) have been used to study the electronic structure of NiTi (100) surface, molecular O2 and adsorption of O2 on the NiTi alloy (100) surface. The results show that Ti-terminated surface is more reactive than Ni-terminated surface. O2 is activated and will decompose upon adsorption. Among several possible adsorption configurations considered, the most stable one corresponds to bridge configuration and the top configuration is unstable. Structural and density of state (DOS) analysis shows the interaction of O atom and surface is the total contribution of valance orbital of O atom and hybridized surface orbital of NiTi alloy.
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