期刊
JOURNAL OF COMPUTATIONAL CHEMISTRY
卷 30, 期 12, 页码 1910-1922出版社
WILEY
DOI: 10.1002/jcc.21174
关键词
DFT; Pd clusters; nitrogen oxide adsorption
资金
- Austrian Science Funds [P19983, P19712]
- Austrian Science Fund (FWF) [P19983, P19712] Funding Source: Austrian Science Fund (FWF)
The adsorption of NO molecules oil small Pd-n (n = 1-6) clusters has been studied using first-principles density-functional theory. Three adsorption sites were considered: vertex (on-top), bridge, and hollow. Adsorption is strong, ranging from 2 to 3 eV. In all cases NO adsorbs in a bent configuration. Calculated shifts in N-O bond vibration frequencies (with anharmonic corrections) agree very well with available experimental data. In contrast to metallic Pd surfaces, adsorption of NO on palladium clusters causes considerable changes in geometry around adsorption site because palladium d-orbitals rehybridize to maximize the overlap with NO orbitals (mainly the antibonding pi*). Thus, the overall energetic effect of NO adsorption is the result of two competing processes: lowering of the total energy through tighter bonding with NO and rising the energy due to Cluster deformation. The Pd-n-NO bond creation is governed by electron transfer from Pd-d orbitals into the NO pi*. As a result. the Pd Cluster becomes locally demagnetized (with total magnetic moment of 1 mu(B) located at Pd atoms not connected to NO) and the NO molecule is activated: the N-O bond length is increased and the vibration frequency is redshifted. (C) 2009 Wiley Periodicals, Inc. J Comput Chem 30: 1910-1922, 2009
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