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在密度泛函理论下,计算了清洁和吸附氧原子的Cu(100)表面的驰豫和优势吸附构型。结果表明,氧原子在金属表面采用四重穴位时,具有最大的结合能,顶位吸附时结合能最小,桥位吸附时结合能居间。这一计算结果与实验报道一致。各种密度泛函方法的比较后,发现采用mPW1PW91密度泛函和LanL2dz赝势基组,能够准确给出与实验相符的计算结果。平板模型计算的分态密度图显示,在吸附过程中出现d轨道向Fermi能级移动并越过Fermi能级,而O原子的p轨道能级远离Fermi能级,表明有电子从铜原子的d轨道转移到氧原子的2p轨道,簇模型和平板模型的布居分析显示表面氧带有约0.65～0.7 e的负电荷。研究表明,采用适当的基组和泛函方法,即使采用簇模型来模拟表面,也可以获得与实验比较吻合的计算结果。
Based on the density functional theory, the relaxation and the predominant adsorption configuration of the Cu (100) surface which clean and adsorb oxygen atoms have been calculated. The results show that the oxygen atom has the maximum binding energy when the metal surface adopts four points, the binding energy is the smallest when the top position is adsorbed, and the binding energy when the position is adsorbed is intermediate. This calculation is consistent with the experimental report. After comparison of various density functional methods, it is found that the mPW1PW91 density functional group and the LanL2dz pseudopotential base group can be used to accurately calculate the experimental results. Fractional density maps calculated by the plate model show that during the adsorption process, the d orbital moves towards the Fermi level and crosses the Fermi level, while the p orbital level of the O atom departs from the Fermi level, indicating that there is electron from the d orbit of the copper atom The population analysis of the 2p orbit, cluster model and plate model shifted to oxygen atoms showed that the surface oxygen band has a negative charge of about 0.65-0.7 e. The results show that, with proper basis set and functional method, even the cluster model can be used to simulate the surface, the experimental results are in good agreement with the experimental ones.