Wn (n= 1–6)团簇吸附CO的密度泛函研究

采用密度泛函理论(density functional theory, DFT) 在B3LYP/LANL2DZ基组水平上对钨团簇吸附CO分子进行了系统研究. 结果表明, W_nCO团簇的基态结构是在W_n团簇中性或阴离子基态结构的基础上吸附CO生长而成; CO的吸附以端位吸附为主,桥位吸附为辅; CO分子在W_n团簇表面发生的是非解离性吸附. 与优化的CO键长(0.116 nm)相比,吸附后C-O键长变长(0.120–0.123 nm), 表明吸附后C-O键被削弱, CO分子被活化了.稳定性分析表明,在所研究的团簇中, W₃CO和W₅CO团簇的稳定性较强;自然键轨道(NBO)分析表明, W原子与CO分子相互作用的本质是CO分子内的杂化轨道与W原子6s, 5d, 6p和6d轨道相互作用的结果. 关键词： nCO (n= 1–6)团簇')" href="#">W_nCO (n= 1–6)团簇 基态构型 稳定性 电子性质

Density functional theory study of the adsorption of CO on Wn (n= 1–6) clusters

CO molecules adsorbed on the W_n clusters are systematically investigated by using density functional theory at the B3LYP/LANL2DZ level.The result indicates that the ground state structures of W_nCO clusters are generated when CO molecules are adsorbed on W_n clusters or anionic cluster. We find that among the molecular adsorption states exists mainly the form of end-on type geometry, and that the bridge site adsorption type geometry plays a supplementary role. On the face, the adsorption is a non-dissociative adsorption. The CO bond length increases 0.120–0.123 nm in W_nCO cluster (compared with 0.116 nm in free CO molecule), which demonstrates that the CO molecules are activated. The stability analysis shows that W₃CO and W₅CO clusters are more stable than other clusters; natural bond orbital (NBO) analysis indicate that the interaction between W atom and CO molecule is primarily contributed by hybridization of molecular orbits within CO and 6s, 5d, 6p and 6d orbits of W atoms.