Potential Energy Curves, Spectroscopic Parameters, and Spin鈥揙rbit Coupling: A Theoretical Study on 24 螞-S and 54 惟 States of C2+ Cation

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• 作者：Deheng Shi ; Xianghong Niu ; Jinfeng Sun ; Zunlue Zhu
• 刊名：The Journal of Physical Chemistry A
• 出版年：2013
• 出版时间：March 7, 2013
• 年：2013
• 卷：117
• 期：9
• 页码：2020-2034
• 全文大小：509K
• 年卷期：v.117,no.9(March 7, 2013)
• ISSN：1520-5215

文摘

The potential energy curves (PECs) of 24 螞-S states and 54 惟 states of the C₂⁺ cation are studied in detail using an ab initio quantum chemical method. All the PEC calculations are made for internuclear separations from 0.09 to 1.11 nm by the complete active space self-consistent field method, which is followed by the internally contracted multireference configuration interaction approach with the Davidson modification (MRCI+Q). All the 螞-S states involved dissociate into the first dissociation limit, C(³P_g) + C⁺(²P_u), of C₂⁺ cation, of which only the 2²危_g^{鈥?/sup> and 24危_g鈥?/sup> are repulsive. The spin鈥搊rbit (SO) coupling effect is accounted for by the Breit鈥揚auli Hamiltonian with an aug-cc-pCVTZ basis set. To improve the quality of PECs, core鈥搗alence correlation and scalar relativistic corrections are included. Core鈥搗alence correlation corrections are taken into account with an aug-cc-pCVTZ basis set. Scalar relativistic correction calculations are done by the third-order Douglas鈥揔roll Hamiltonian approximation with the cc-pVQZ basis set. All the PECs are extrapolated to the complete basis set limit. The convergence observations of present calculations are made, and the convergent behavior is discussed with respect to the basis set and level of theory. With the PECs obtained by the MRCI+Q/CV+DK+56 calculations, the spectroscopic parameters of 22 螞-S bound states of C₂+ cation are evaluated by fitting the first ten vibrational levels, which are obtained by solving the rovibrational Schr枚dinger equation using Numerov鈥檚 method. In addition, the spectroscopic parameters of 51 惟 bound states generated from these 螞-S bound states are also obtained. The spectroscopic parameters are compared with those reported in the literature. Excellent agreement with available measurements is found. It is expected that the spectroscopic parameters of 螞-S and 惟 states reported here are reliable predicted ones.}