Departamento de Quı́mica, Universidade de Coimbra , 3004-535 Coimbra, Portugal.
J Phys Chem A. 2013 Sep 12;117(36):8794-805. doi: 10.1021/jp404393n. Epub 2013 Aug 14.
An ab initio quantum dynamics study is performed to examine the complex nuclear motion underlying the first photoelectron band of the silane molecule due to Jahn-Teller distortion via T2⊗(e+t2+t2) coupling. The problem is investigated by employing a quadratic vibronic coupling model for the Hamiltonian. All sheets of the required potential energy surface are established through extensive electronic structure calculations using the multireference configuration-interaction method. They cover at most two dimensions of the full 9D coordinate space, with the parameters defining the model Hamiltonian being determined by a least-squares fitting procedure. The results are compared with the available experimental data and discussed in relation to those obtained for the methane radical cation. The quadratic couplings of Jahn-Teller active vibrational modes are found to have a crucial role on the irregular vibronic structure, intensity of the spectral excitations, and overall width of the first photoelectron band of the title molecule. The impact of large amplitude motions on the vibronic structure and dynamics of the first photoelectron band has also been examined by varying their linear coupling parameters up to ±10%.
采用二次振子耦合模型对该哈密顿量进行研究。通过多参考组态相互作用方法进行广泛的电子结构计算，建立了所需势能面的所有面。它们最多覆盖全 9D 坐标空间的两个维度，模型哈密顿量的参数通过最小二乘法拟合程序确定。结果与可用的实验数据进行了比较，并与甲烷自由基阳离子的结果进行了讨论。发现 Jahn-Teller 活性振动模式的二次耦合对标题分子的第一光电子带的不规则振子结构、光谱激发的强度和整体宽度具有关键作用。还通过将它们的线性耦合参数变化到±10%，研究了大振幅运动对第一光电子带的振子结构和动力学的影响。
