MgO缺陷和不规则表面吸附Cl2的电子结构研究

采用从头算程序对MgO表面 3种不同配位位置吸附Cl2 的构型进行优化 ,并用扩展休克尔紧束缚 (EHT)晶体轨道方法对MgO的缺陷和不规则表面吸附Cl2的可能构型进行能带计算 ,讨论了吸附前后能带组成和成键性质的变化。研究表明 :MgO表面吸附Cl2 将更趋向于吸附在O原子上而非Mg原子上 ,而且在 3种配位中MgO表面三配位氧最有利于吸附Cl2 ;吸附时 ,电子从O原子转移到Cl2 分子的反键轨道 ,但是各种吸附构型的MgO表面对Cl2 的吸附作用均比较微弱 ,是典型的物理吸附。

The Electronic Structure of Cl2 Adsorption on MgO(001) Defective and Irregular Surfaces

Using the geometric configuration optimized from ab initio calculation, the electronic structures of Cl_2 adsorption on MgO(001) defective and irregular surfaces were studied by EHT crystal orbital method. The characteristics of bands have been discussed. The results of the optimization have proved that Cl_2 is preferable to bind over oxygen sites. Moreover, Cl_2 binds at Mg(3C) cations corner sites considerably stronger than at regular Mg(5C) and Mg(4C) sites. The charge redistributions in the Cl_2 molecule and in the substrate are considered. The magnesium vacancy of MgO(001) surface is more beneficial to Cl_2 adsorption and decompose on the surface than other configurations. It is proved that the interactions between the Cl_2 /surface are weak physisorption.