~3Δ、~3Π、~3Σ~+Ni-CO分子簇的从头算研究

Ab Initio Calculations of ￣3Δ, ￣3Π, ￣3Σ￣+Ni-CO Molecular Clusters

用从头算研究了ｄ空穴位置不同对Ｎｉ—ＣＯ成键机制的影响。结果表明，Ｎｉ—ＣＯ键中σ／π接受作用的相对强弱，取决于Ｎｉ—ＣＯ簇所处的能态。σ空间电子云较π空间电子云弥散，因而Ｎｉ—ＣＯ簇的稳定性与σ空间电子云的排斥密切相关。随着Ｎｉ４ｐσ轨道上电子占据数的增加，Ｎｉ—ＣＯ稳定性减弱。比较了分子簇Ｎｉ—ＣＯ与ＮｉＣＯ分子及ＣＯ／Ｎｉ化学吸附体系之间的性质。

Ab initio methods are employed to study the influence of the d-hole position upon the Ni-CO bonding mechanism. The calculation results demonstrate that the relative importance of σ-donation and π-backdonation varies with the electronic states of Ni-CO. The electron cloud in σ subspace is more diffuse than that in π subspace,thus the stability of Ni-CO is closely related to the electronic repulsion in σ subspace. With the increase of the Ni 4pσ occupation, the stability of Ni-CO decreases. Combinebd with the previous results,a comparison between Ni-CO molecular cluster and NiCO molecule, as well as CO/Ni chemisorption system, is given.