Abstract Using the different level of methods B3P86, BLYP、B3PW91, HF, QCISD、CASSCF (4,4) and MP2 with the various basis functions 6-311G**, D95, cc--pVTZ and DGDZVP, the calculations of this paper confirm that the ground state is $\tilde {X}{ }^3B_1 $ with $C_{2v} $ group for CH$_{2}$. Furthermore, the three kinds of theoretical methods, i.e. B3P86、CCSD(T, MP4) and G2 with the same basis set cc-pVTZ only are used to recalculate the zero-point energy revision which are modified by scaling factor 0.989 for the high level based on the virial theorem, and also with the correction for basis set superposition error. These results are also contrary to $\tilde {X}{ }^3\varSigma _{\rm g} ^ - $ for the ground state of CH$_{2}$ in reference. Based on the atomic and molecular reaction statics, this paper proves that the decomposition type (1) i.e. CH$_{4}\to $CH$_{2}$+H$_{2}$, is forbidden and the decomposition type (2) i.e. CH$_{4} \to $CH$_{3}$+H is allowed for CH$_{4}$. This is similar to the decomposition of SiH$_{4}$.
Received: 06 June 2007
Revised: 28 September 2007
Accepted manuscript online:
PACS:
82.30.Lp
(Decomposition reactions (pyrolysis, dissociation, and fragmentation))
(Atom and radical reactions; chain reactions; molecule-molecule reactions)
Fund: Project supported by the Joint
Funds of the National Natural
Science Foundation of China (Grant No 10576029).
Cite this article:
Zhang Li(张莉), Luo Wen-Lang(罗文浪), Ruan Wen(阮文), Jiang Gang(蒋刚), and Zhu Zheng-He(朱正和) Ground state for CH2 and symmetry for methane decomposition 2008 Chin. Phys. B 17 2023
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