An Ab Initio Study of the Low-Lying Electronic States of YO2 and Franck−Condon Simulation of the First Photodetachment Band of YO2−

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• 作者：Edmond P. F. Lee ; John M. Dyke ; Daniel K. W. Mok ; Foo-tim Chau
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：May 15, 2008
• 年：2008
• 卷：112
• 期：19
• 页码：4511 - 4520
• 全文大小：142K
• 年卷期：v.112,no.19(May 15, 2008)
• ISSN：1520-5215

文摘

A variety of density functional theory and ab initio methods, including B3LYP, B98, BP86, CASSCF, CASSCF/RS2, CASSCF/MRCI, BD, BD(T), and CCSD(T), with ECP basis sets of up to the quintuple-zeta quality for Y, have been employed to study the X<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>²B₂ state of YO₂ and the X<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>¹A₁ state of YO₂⁻. Providing that the Y 4s²4p⁶ outer-core electrons are included in the correlation treatment, the RCCSD(T) method gives the most consistent results and is concluded to be the most reliable and practical computational method for YO₂ and YO₂⁻. In addition, RCCSD(T) potential energy functions (PEFs) of the X<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>²B₂ state of YO₂ and the X<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>¹A₁ state of YO₂⁻ were computed, employing the ECP28MDF_aug-cc-pwCVTZ and aug-cc-pVTZ basis sets for Y and O, respectively. Franck−Condon factors, which include allowance for Duschinsky rotation and anharmonicity, were calculated using the computed RCCSD(T) PEFs and were used to simulate the first photodetachment band of YO₂⁻. The simulated spectrum matches very well with the corresponding experimental 355 nm photodetachment spectrum of Wu, H.; Wang, L.-S. J. Phys. Chem. A 1998, 102, 9129, confirming the reliability of the RCCSD(T) PEFs used. Further calculations on low-lying electronic states of YO₂ gave T_e's and T_vert's of the A<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>²A₁, B<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>²B₁, and C<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>²A₂ states of YO₂, as well as EAs and VDEs to these states from the X<font face="Arial Unicode MS,Lucida Sans Unicode,Code2000,GNU Unifont">̃font>¹A₁ state of YO₂⁻. On the basis of the ab initio VDEs obtained in the present study, previous assignments of the second and third photodetachment bands of YO₂⁻ have been revised.