烯烃分子在氢终止Si(100)-2×1表面的自由基链反应

Radical Chain Reaction of Alkene Molecule on H-terminated Si(100)-2×1 Surface

应用密度泛函理论(DFT)和从头计算分子动力学方法(abinitioMD)研究了不饱和烯烃在氢终止的Si(100)-2×1表面的自由基链反应.计算表明,自由基链反应中重要的一步是烷烃链自由基的氢抽提过程,硅表面上邻近位置(the nearest neighbor,NN)的氢抽提比次邻近位置(thenext-nearest neighbor,NNN)的氢抽提有一稍低的能垒.从头算分子动力学显示,过渡态的烷烃自由基与氢终止Si(100)-2×1表面上的氢原子能够很容易形成C—H键,完成一个氢抽提过程,同时在硅表面产生下一个孤电子,继续引发链反应.

The density functional theory and ab initio molecular dynamic method were applied on the radical initiated chain reaction of unsaturated 1-alkene molecules on H-terminated Si（100）-2×1 surface. The results showed that the crucial step of the surface chain reaction, namely, the abstraction of a H atom from a nearby surface hydride unit, had a somewhat smaller activation energy from the nearest silicon site than that from the next nearest silicon site. Ab initio molecular dynamics showed that the H-abstraction on Si（100）-2×1 surface bound organic group with a carboncentered radical was very easy to be obtained from the transition state, and a new silicon dangling bond was produced to lead to a surface chain reaction.