C_2H_x(x=4～6)在Ni(111)表面吸附的DFT研究

Density functional theory study of C_2H_x(x=4～6)adsorption on Ni(111)surface

采用密度泛函理论与周期平板模型相结合的方法,对物种C_2H_x(x=4～6)在Ni(111)表面的top,fcc,hcp和bridge位的吸附模型进行了结构优化、能量计算,得到了各物种较有利的吸附位;并对最佳吸附位进行密立根电荷和总态密度分析.结果表明:C_2H_6和C_2H_4在Ni(111)表面的最稳定吸附位都是top位,吸附能分别是-36.41和-48.62 kJ·mol^(-1),物种与金属表面吸附较弱;而C_2H_5在Ni(111)表面的最稳定吸附位hcp的吸附能是-100.21 kJ·mol^(-1),物种与金属表面较强;三物种与金属表面之间都有电荷转移,属于化学吸附.

The density functional theory （DFT） and self-consistent periodic calculation were used to investigate the species C2 Hx（x=4-6） adsorption on Ni（lll） surface. The adsorption energy, equilibrium geometry of the species C2Hx（x=4-6） on four possible sites （top, fcc, hcp, and bridge） on Ni （111） surface were predicted and compared. Mulliken charges and density of states analysis of the most stable site have been discussed. It is found that the species C2HGand C2H4 adsorbs feebly on Ni （111） surface with calculated adsorption energy of -36.41 and -48.62 kJ · mol^-1 at the Ni-top（top）, respectively. However, the C2 Hs adsorb strongly at threefold hollow sites with calculated adsorption energies of -100.21 kJ · mol^-1 at the hcp. The results indicate that the charge transferring process can be completed by chemisorption between Ni（111） surface and the species. Moreover, the chemical bands can be formed by chemisorption between Ni（111） surface and the species, too.