Geometrical and Electronic Characteristics of AunO2鈥?/sup> (n = 2鈥?)
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- 作者：Han Myoung Lee ; Kee Hag Lee ; Geunsik Lee ; Kwang S. Kim
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：June 25, 2015
- 年：2015
- 卷：119
- 期：25
- 页码：14383-14391
- 全文大小：316K
- ISSN：1932-7455
文摘
Most density functionals do not properly describe the characteristics of superoxide (O2鈥?/sup>) (i.e., first two vertical electron detachment energies and the excitation energies of neutralized singlet state) of small even-numbered AunO2鈥?/sup> clusters. However, the second-order M酶ller鈥揚lesset theory (MP2) shows significant charge transfer from Au cluster anions to oxygen molecule and so provides proper electronic characteristics of superoxide of small even-numbered AunO2鈥?/sup> clusters. This has allowed us to properly describe the properties of even-numbered AunO2鈥?/sup> clusters. Even in the case of odd-numbered AunO2鈥?/sup> clusters, we find that Au5鈥?/sup> is a chemically O2-adsorbed singlet state at 0 K, against a commonly accepted physisorbed triplet state. This is further evidenced by our extensive coupled cluster with single, double, and perturbative triple excitations [CCSD(T)] calculations, including the relativistic effect. However, the entropy effect makes the physisorbed triplet state more stable than the chemisorbed singlet state at higher temperatures, consistent with the experiment. The weak O2 binding by odd-numbered cluster anions (n = 3, 5, and 7) could be further weakened by the entropic effect, which results in van der Waals complexes at high temperatures. The present study reports the geometrical and electronic characteristics of small AunO2鈥?/sup> (n = 2鈥?) clusters including isomers, which match the corresponding photoelectron spectra (PES).