Wasada-Tsutsui Yuko, Watanabe Yoshihiro, Tatewaki Hiroshi
Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya, 467-8501, Japan, and Department of Chemistry, Faculty of Science, Kyushu University, Hakozaki, Fukuoka, 812-8581, Japan.
J Phys Chem A. 2007 Sep 13;111(36):8877-83. doi: 10.1021/jp0709149. Epub 2007 Aug 18.
We study the electronic structure of the ground and several low-lying states of the CeF molecule using Dirac-Fock-Roothaan (DFR) and four-component relativistic single and double excitation configuration interaction (SDCI) calculations in the reduced frozen-core approximation (RFCA). The ground state and two low-lying excited states are calculated to have (4f)1(5d)1(6s)1 configurations with Omega = 3.5, 4.5, and 3.5, and the resulting excitation energies, T0, are, respectively, 0.319 and 0.518 eV. The experimental configurations for these states are the same, although the experimental T0 values are approximately 0.3 eV smaller than those calculated. Experimentally, the red-degraded band was observed to be 2.181 eV above the ground state, having the configuration (4f)1(5d)1(6p)1 with Omega = 4.5. The calculation for this state gives 2.197 eV and configuration (4f)1.0(5d)1.7(6p)0.3 with Omega = 4.5. We found that Omega, Re, and nu(1-0) obtained by CI agree well with experiment. Bonding between the Ce and the F is highly ionic. The 4f, 5d, and 6s valence electrons are localized at the Ce+ ion, because they are attracted by the Ce4+ ion core, and are excluded from the bonding region because of the electronic cloud around the negatively charged fluoride anion. The bonding in the ground and excited states of the CeF molecule is significantly influenced by the 6s and 5d electron distributions between the Ce and the F.
我们使用狄拉克 - 福克 - 罗特汉（DFR）方法以及在约化冻结芯近似（RFCA）下的四分量相对论单双激发组态相互作用（SDCI）计算，研究了CeF分子基态和几个低激发态的电子结构。计算得出基态和两个低激发态具有(4f)1(5d)1(6s)1组态，Ω值分别为3.5、4.5和3.5，相应的激发能T0分别为0.319和0.518电子伏特。这些态的实验组态相同，不过实验测得的T0值比计算值小约0.3电子伏特。实验上，观察到红移退化带比基态高2.181电子伏特，具有(4f)1(5d)1(6p)1组态，Ω = 4.5。该态的计算结果为2.197电子伏特，组态为(4f)1.0(5d)1.7(6p)0.3，Ω = 4.5。我们发现通过CI得到的Ω、Re和ν(1 - 0)与实验结果吻合良好。Ce和F之间的键合具有高度离子性。4f、5d和6s价电子定域在Ce + 离子处，因为它们被Ce4 + 离子核吸引，并且由于带负电的氟阴离子周围的电子云而被排除在键合区域之外。CeF分子基态和激发态的键合受Ce和F之间6s和5d电子分布的显著影响。
