Theoretical insight into electronic spectra of carbon chain carbenes H2Cn (n = 3-10).
Theoretical insight into electronic spectra of carbon chain carbenes H2Cn (n = 3-10).
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DOI：
10.1063/1.4806186
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发表时间：
2013-05
期刊：
影响因子：
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通讯作者：
Yanxin Zhang;Li Wang;Yuanyuan Li;Jinglai Zhang
中科院分区：
文献类型：
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作者：
Yanxin Zhang;Li Wang;Yuanyuan Li;Jinglai Zhang
在C2ν-对称性约束下，分别在密度泛函理论和限制自旋耦合团簇单双加微扰三重激发水平上，对卡宾H2 Cn（n = 3-10）的基态几何结构进行了全优化.用完全的活性空间自洽场计算比较了X（1）A1和B（1）B1电子态的结构。在本研究中发现了宇称交替效应对基态几何结构的各种性质的影响，从总体上说明了标题碳链的相对稳定性。采用完全活性空间二级微扰理论方法沿着cc-pVTZ基组对它们的电子光谱进行了进一步的计算。结果表明，气相中偶极允许的B（1）B1 ← X（1）A1跃迁的垂直激发能分别为2.28，4.75，1.69，3.66，1.30，2.94，1.12和2.49 eV，与H_2C_3的实验结果（2.27 eV）吻合得很好.此外，通过曲线拟合，发现B（1）B1 <$X（1）A1和A（1）A2 <$X（1）A1的垂直激发能随链长的变化服从非线性ΔE-n关系.
Ground-state geometries of carbenes H2Cn (n = 3-10) have been fully optimized with the C2ν-symmetry constraint at the density functional theory and restricted-spin coupled-cluster single-double plus perturbative triple excitation levels of theory, respectively. Comparison of structures corresponding to the X(1)A1 and B(1)B1 electronic states has been made by the complete active space self-consistent field calculations. Parity alternation effect on various properties of the ground-state geometries has been discovered in the present study, which generally gives illustration for the relative stabilities of the titled carbon chains. Further calculations on their electronic spectra have been carried out by means of the complete active space second-order perturbation theory method along with the cc-pVTZ basis set. It is found that the vertical excitation energies of the dipole-allowed B(1)B1 ← X(1)A1 transition in the gas phase are 2.28, 4.75, 1.69, 3.66, 1.30, 2.94, 1.12, and 2.49 eV, respectively, which agree very well with the available experimental result for H2C3 (2.27 eV). In addition, the vertical excitation energies for both transitions B(1)B1 ← X(1)A1 and A(1)A2 ← X(1)A1 are found to obey a nonlinear ΔE-n relationship as a function of chain size by performing curves fitting.