CN~+离子电子结构和跃迁性质的理论研究
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摘要
采用多组态参考相互作用方法和AV5Z-DK基组对CN~+离子的两个解离极限C~+(~2P_u)+N(~2D_u)和C~+(~2P_u)+N(~4S_u)下的X~1Σ~+、a~3Π、~1Δ和A~1四个电子态的势能曲线、永久偶极矩和振动能级进行了计算.为保证计算结果的精确性,在计算中考虑了Davidson修正.基于求得的势能曲线,数值求解一维径向薛定谔方程得到了各个电子态的光谱数据,并与实验值和已有的理论值吻合较好.除此之外,对A~1Π→X~1Σ~+和1~1Δ?A1~Π的跃迁性质进行了研究,同时通过跃迁的弗兰克-康登因子及辐射寿命,对CN~+离子激光冷却的可行性进行了分析.
The potential energy curves, permanent dipole moments and vibration energy levels of low-lying electronic states X~1Σ~+, a~3Π, ~1Δ, and A~1 with the two dissociation channels C~+(~2P_u)+N(~2D_u) and C~+(~2P_u)+N(~4S_u) for CN~+ ion are determined with the multi-reference configuration interaction based on AV5 Z-DK basis set. Davidson correction is considered in the calculation to ensure the accuracy of the calculation results. Based on the potential energy curve, the calculated spectroscopic constants of each electron state are obtained by solving the one-dimensional radial Schr?dinger equation numerically which are in well agreement with the available experimental data and previous theoretical values. In addition, the transition properties of A~1Π→X~1Σ~+ and 1~1Δ?A1~Π are studied, and the feasibility of laser cooling of CN~+ ions is analyzed by the Franck-Condon factor and radiative lifetime of the transition.
The potential energy curves, permanent dipole moments and vibration energy levels of low-lying electronic states X~1Σ~+, a~3Π, ~1Δ, and A~1 with the two dissociation channels C~+(~2P_u)+N(~2D_u) and C~+(~2P_u)+N(~4S_u) for CN~+ ion are determined with the multi-reference configuration interaction based on AV5 Z-DK basis set. Davidson correction is considered in the calculation to ensure the accuracy of the calculation results. Based on the potential energy curve, the calculated spectroscopic constants of each electron state are obtained by solving the one-dimensional radial Schr?dinger equation numerically which are in well agreement with the available experimental data and previous theoretical values. In addition, the transition properties of A~1Π→X~1Σ~+ and 1~1Δ?A1~Π are studied, and the feasibility of laser cooling of CN~+ ions is analyzed by the Franck-Condon factor and radiative lifetime of the transition.
引文
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[2] Douglas A E,Routly P M.On the spectra of the CN+ and CN molecules.[J].Astrophys.J.,1953,117 :461.
[3] Lutz B L.The emission spectrum of CN+ [J].At.Data Nucl.Data Tables.,1976,18:459.
[4] Wu A J A.A CI procedure using SCF MOs as basis functions.Application to HNO and NCO+ [J].Chem.Phys.,1977,21:173.
[5] Shimakura N,Inouye H,Honjou N,et al.Valence full configuration interaction calculation of the CN+ ion [J].Chem.Phys.Lett.,1978,55:221.
[6] Wu A A.SCF potential energy curves of CN+.The identify of the ground state [J].Chem.Phys.Lett.,1978,59:457.
[7] Hirst D M.Ab initio potential curves for the lowest 1Σ+ and 3∏ states of the ion CN+ [J].Chem.Phys.Lett.,1979,65:181.
[8] Murrell J N,Al-Derzi A,Tennyson J,et al.Potential energy curves of the lower states of CN+ [J].Mol.Phys.,1979,38:1755.
[9] Bruna P J,Peyerimhoff S D,Buenker R J.The ground state of the CN+ ion:a multi-reference Ci study [J].Chem.Phys.Lett.,1980,72:278.
[10] Swamy K,K.S.Intensities of various bands of the molecules CN,CN+,and CS in comets [J].Astron.Astrophys.,1981,97:110.
[11] Roos B O,Linse P.A simple method for the evaluation of the second-order-perturbation energy from external double-excitations with a CASSCF reference wavefunction [J].Chem.Phys.,1982,66:197.
[12] Hirst D.Excited states of the CN+ ion:an ab initio study [J].Mol.Phys.,1994,82:359.
[13] Peterson K A.Accurate multireference configuration interaction calculations on the lowest 1Σ+ and 3∏ electronic states of C2,CN+,BN,and BO+ [J].J.Chem.Phys.,1995,102:262.
[14] Rajamanickam N,Nagarajan K,Raja V.Franck-Condon factors and centroids for certain band systems of astrophysical molecular ions CN+ and N2+ [J].Astrophys.Space.Sci.,2000,274:725.
[15] Polák R,Fiser J.Multireference CI calculation of nuclear quadrupole coupling constants of CN+ and CN-:rovibrational dependence [J].Spectrochim.Acta.Part A:Mol.Biomol.Spectrosco.,2002,58:2029.
[16] Liao J W,Yang C L.MRCI study on the analytical potential energy function and spectroscopic parameters of CN+ molecule [J].Chem.Res.Appl.,2015,27:472 (in Chinese) [廖建文,杨传路.CN+分子势能函数和光谱常数的多参考组态相互作用方法研究 [J].化学研究与应用,2015,27:472]
[17] Belic D S,Urbain X,Cherkani-Hassani H,et al.Electron-impact dissociation and ionization of CN+ ions [J].Phys.Rev.A,2017,49:135202.
[18] Le Roy R J.LEVEL 8.2:A Computer Program for Solving the Radial Schrodinger equation for Bound and Quasibound Levels.[M].University of Waterloo:Chemical Physics Research,Report CP-668,2015.
[19] H.J.Werner,P.J.Knowles,G.Knizia,F.R.Manby,and M.Schütz,MOLPRO,a package of ab initio programs,version 2015.1
[20] Knowles P J,Werner H J.The Multi Configuration SCF Program [J].J.Chem.Phys.,1985,82:5053.
[21] Knowles P J,Werner H J.An efficient second-order MCSCF method for long configuration expansions [J].Chem.Phys.Lett.,1985,115:259.
[22] Wu D L,Tan B,Wen Y F,et al.The spectroscopic constants and molecular constants of low – lying excited states of MgH molecule[J].J.At.Mol.Phys.,2016,33:785 (in Chinese) [伍冬兰,谭彬,温玉锋,等.MgH分子低激发态的光谱和分子常数[J].原子与分子物理学报,2016,33:785]
[23] Wu D L,Tan B,Wen Y F,et al.The spectroscopic and molecular constants of low – lying excited states of MgCl molecule by multi – reference configuration interaction method[J].J.At.Mol.Phys.,2018,2:186 (in Chinese) [伍冬兰,谭彬,温玉锋,等.多参考组态相互作用方法研究MgCl分子低激发态的光谱和分子常数[J].原子与分子物理学报,2018,2:186]
[24] Langhoff S R,Davidson E R.Configuration interaction calculations on the nitrogen molecule [J].Int.J.Quantum.Chem.,1974,8:61.
[25] Knowles P J,Werner H J.An efficient method for the evaluation of coupling coefficients in configuration interaction calculations [J].Chem.Phys.Lett.,1988,145:514.
[26] Werner H,Knowles P J.An efficient internally contracted multiconfiguration–reference configuration interaction method [J].J.Chem.Phys.,1988,89:5803.
[27] Douglas M,Kroll N M.Quantum electrodynamical corrections to the fine structure of helium [J].Ann.Phys.,1974,82:89.
[28] Hess B A.Relativistic electronic-structure calculations employing a two-component no-pair formalism with external-field projection operators[J].Phys.Rev.A,1986,33:3742.
[29] Herzberg G,Mrozowski S.Molecular Spectra and Molecular Structure [M].I.Spectra of Diatomic Molecules.Van Nostrand:New York,1950.
[30] Bernath P F,Knee J L.Spectra of atoms and molecules [J].Am.J.Phys.,1996,49:93.