CH_3CN分子价壳层轨道电子动量分布的理论研究

Theoretical Research of the Electron Momentum Distribution of the Valence Shell Orbitals for CH_3CN

采用密度泛函理论DFT-B3LYP方法,选用6-31G,6-311++G,6-311++G(d,p)和AUG-cc-pVTZ基组以及HF方法选用AUG-cc-pVTZ基组对CH3CN分子价壳层轨道电子动量分布进行了研究。理论计算与前人实验结果和利用Snyder和Basch波函数以及HF方法选用431G基组计算得到的理论的动量分布进行了比较。总体而言,除DFT-B3LYP/631G外,采用的其它几种计算均较前人理论计算与实验结果符合更好。对外价轨道7a1,1e和6a1,轨道电子的弥散效应很明显,而轨道的极化效应不明显,且7a1和6a1轨道的电子关联效应比较显著。对内价轨道,不同基组计算结果之间差别很小,表明内价壳层轨道极化和弥散效应很弱。

The valence shell orbital electron momentum distribution for CH3CN have been studied by DFT- B3 LYP method with 6-31 G,6-311 ＋ ＋G, 6-311 ＋ 4G （ d, p） and AUG-cc-pVTZ basis sets. They are also been calculated by HF method with AUG-cc-pVTZ basis sets. The theoretical calculations are compared with previous experimental and Snyder and Basch wavefunction and HF/4-31 G theoretical results. Generally, compareing with previous calculations, except DFT-B3 LYP/6-31 G, our theoretical calculations all give better description for experimental resuits. For outer valence orbitals 7a1. 1e and 6a1 , it is found a great electron-dispersion effect, but the polarization effect is unconspicuous for these orbitals. And there is an obvious electron correlation effect for 7a1 and 6a1 orbitals. For inner valence orbitals, there is almost no discrepancy among theoretical results. The polarization and dispersion effects are weak for inner valence orbitals.