Ab initio studies of electronic spectra of the linear aluminum-bearing carbon chains AlC2nH (n=1-5)

作者：Guo Xugeng; Wang Shoubin; Li Junfeng; Jiang Lihui; Zhang Jinglai^*

来源：Journal of Molecular Spectroscopy, 2009, 256(2): 242-246.

DOI：10.1016/j.jms.2009.04.014

• AlC2nH (n=1-5)
• ab initio studies
• Electronic spectra
• Dissociation energies
• Exponential-decay curves

Geometries and stabilities of the linear aluminum-bearing carbon chains AlC2nH (n = 1-5) in their ground states have been explored by the DFT-B3LYP and RCCSD(T) methods. Structures of the X-1 Sigma( ) and 1(1)Pi electronic states have also been optimized by the CASSCF approach. The studies indicate that these species have single-triple bond alternate pattern, A1-C C-C C center dot center dot center dot C C-H, and the electronic excitation from X-1 Sigma( ) to 1(1)Pi leads to the shortening of the Al-C bonds. The vertical excitation energies ofthe 1(1)Pi <- X-1 Sigma( ) and 2(1)Pi <- X-1 Sigma( ) transitions for AlC2nH (n = 1-5) have been investigated by the CASPT2, EOM-CCSD, and TD-B3LYP levels of theory with the cc-pVTZ basis set, respectively. CASPT2-predicted 1(1)Pi <- X-1 Sigma( ) transition energies are 3.57, 3.44, 3.33, 3.26, and 3.21 eV, respectively. For AlC2H, our estimate agrees very well with the experimental value of 3.57 eV. In addition, the Al-C bond dissociation energies and the exponential-decay curves for these vertical excitation energies are also discussed.

• 出版日期2009-8
• 单位河南大学