基于密度泛函理论的第一性原理方法，建立ZnO(100)和ZnO(001)表面的吸附模型，计算了吸附能、电荷密度、态密度以及过渡态等参数，研究了CH3Cl在ZnO不同表面、不同位点、不同吸附方式的吸附情况。结果表明，CH3Cl在ZnO(100)和ZnO(001)表面的吸附过程均为化学吸附。当CH3Cl整体吸附时，CH3Cl分子中的Cl原子可以与ZnO表面的Zn(2a)原子生成Zn-Cl键，CH3Cl在ZnO(100)表面的吸附能比在ZnO(001)表面的吸附能更低(-0.57 eV vs. -0.42 eV)，体系更稳定；并且CH3Cl在ZnO(100)面吸附后，Cl原子的3p轨道态密度峰向左移动，且靠近费米能级处的峰值降低，表明Cl原子在吸附过程中提供电子，与Zn形成更稳定的相互作用。当CH3Cl解离吸附时，甲基自由基中的C原子可以分别与ZnO(100)表面的O(2a)和O(3a)吸附，CH3Cl解离吸附在Zn(2a)和O(2a)原子处的吸附能为-1.09 eV，在费米能级左侧O 2p轨道和C 2p轨道存在3个共振峰，证明C原子和O原子有较强的相互作用，而在Zn(2a)和O(3a)原子处的吸附能为-1.02 eV，且费米能级右侧O 2p轨道和C 2p轨道存在1个共振峰，表明C和O原子存在反键作用。过渡态的计算结果表明，CH3Cl解离吸附在Zn(2a)和O(2a)位点的过渡态能垒比在Zn(2a)和O(3a)位点更低(1.69 eV vs. 2.06 eV)，因此CH3Cl解离吸附反应倾向于在ZnO(100)表面上相邻的Zn和O原子之间发生。

Based on the first principles method of density functional theory, the adsorption models of ZnO(100) and ZnO(001) surfaces were established to investigate the adsorption and reaction mechanisms of CH3Cl on ZnO surface through considering the adsorption sites, adsorption energy, charge density, density of states and transition state. The simulated results indicated that the adsorption of CH3Cl on both ZnO(100) and ZnO(001) surfaces was chemical adsorption. When CH3Cl was completely adsorbed, a weak chemical bond was formed between Cl and Zn atoms on ZnO surface. The adsorption of CH3Cl on ZnO(100) surface was more stable because the adsorption energy (-0.57 eV) of CH3Cl on ZnO(100) surface was lower than that (-0.42 eV) on ZnO(001) surface. When CH3Cl was adsorbed on ZnO(100) surface, the peaks of state density formed by the 3p orbital of Cl atom shifted to the left and the peak value near the Femi level was diminished comparing with that before the adsorption of CH3Cl. Thus the bonding effect of CH3Cl on ZnO(100) surfaces was more stronger and improved the stability of the system. During the dissociative adsorption of CH3Cl, the C atoms in methyl radical can be adsorbed to O(2a) and O(3a) on the surface of ZnO(100), respectively. The adsorption energy of CH3Cl dissociation adsorption on Zn(2a)/O(2a) site was -1.09 eV. There were three resonance peaks between O 2p and C 2p orbitals on the left side of the Fermi level. It was proved that there was a strong interaction between C and O atoms. On the other hand, the adsorption energy for CH3Cl dissociating on Zn(2a)/O(3a) site was -1.02 eV, and there was a resonance peak of O 2p and C 2p orbitals on the right side of Fermi level, indicating that there was a certain antibonding interaction between C and O atoms. The calculation results of reaction path way showed that the transition state energy of CH3Cl dissociation adsorption at Zn(2a)/O(2a) site was 1.69 eV, while it was 2.06 eV at Zn(2a)/O(3a) site. Therefore, the dissociation adsorption reaction of CH3Cl tends to occur at Zn(2a)/O(2a) site and to form the stable structure.