Impurity Effects on Small Pd Clusters: A Relativistic Density Functional Study of Pd4X, X = H, C, O

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• 作者：Alexander Genest ; Sven Krü ; ger ; Notker R&#246 ; sch
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：August 21, 2008
• 年：2008
• 卷：112
• 期：33
• 页码：7739-7744
• 全文大小：165K
• 年卷期：v.112,no.33(August 21, 2008)
• ISSN：1520-5215

文摘

We carried out relativistic density functional calculations to investigate systematically the effect of main group element impurities H, C, and O on a Pd₄ cluster. We determined a bridging coordination for Pd₄H as most stable, whereas several other local minima are energetically close. The interaction of C with Pd₄ is strong enough to restructure the cluster, resulting in two Pd₂ units bridged by 4-fold coordinated C, but other isomers are again almost degenerate. Nearly degenerate isomers of Pd₄O exhibit 2- and 3-fold coordination of O. In the most stable structures, the binding energies of the impurities, 295 kJ/mol for Pd₄H, 655 kJ/mol for Pd₄C, and 367 kJ/mol for Pd₄O, are large enough to allow bond breaking of common small molecules when they interact with an ensemble of Pd₄ clusters. Interestingly, the noteworthy relativistic effect on the properties of Pd₄ also affects the interaction with impurity atoms. Comparison with other metals reveals similarities with Ni₄X and differences from Ir₄H, Ir₄C, and Pt₄H.rget id="tbl2" target-type="temp-target">rget>