Be_n(n=1～6)团簇吸附H_2的密度泛函研究

Density Functional Theory for Hydrogen Molecule Adsorption of Be_n(n=1-6) Clusters

采用密度泛函广义梯度近似(GGA)的PW91方法,用全电子基组DNP对Ben(n=2～6)团簇几何结构进行优化,计算了团簇的总能、平均结合能、振动频率、最高已占据轨道能级、最低未占据轨道能级、能隙、垂直电离势和垂直亲和势。在Ben(n=1～6)团簇的顶位、桥位和穴位吸附H2后,进行了吸附物的几何优化和能量计算,得到最佳吸附位,并计算了吸附前后的总态密度和Mulliken电荷布居。结果表明:团簇中Be原子数增多,稳定性增强;吸附H2的吸附能处于0.0061982～0.0089722a.u.之间;随着Be团簇原子数量增加,与H的s-p杂化程度增强;吸附位对应的电荷转移量越大,吸附越牢固。

The geometric structures and electronic property of the beryllium clusters Ben（n=2-6）were investigated by using GGA PW91/DNP based on density functional theory.Total energy,average binding energy,vibrational frequencies,the highest occupied and lowest unoccupied molecular orbitals energy,energy gaps,vertical ionization potential and electron affinities were all calculated.After hydrogen molecule was absorbed at the top,bridge and hollow site,it was calculated in terms of geometric optimization,adsorption energy,and Mulliken atomic population analysis.The results show that the stability of clusters is reinforced gradually due to increasing beryllium atoms.Adsorption energy is in the range of 0.006 198 2-0.008 972 2 a.u.After H2 is adsorbed on the beryllium clusters,the extent of hybridization strengthens with increasing beryllium atoms.The more electric transferred charge of adsorption site is,the stronger adsorption force is.