Electronic signatures of large amplitude motions: dipole moments of vibrationally excited local-bend and local-stretch states of S0 acetylene.
Electronic signatures of large amplitude motions: dipole moments of vibrationally excited local-bend and local-stretch states of S0 acetylene.
复制标题
大振幅运动的电子特征：S0 乙炔振动激发的局部弯曲和局部拉伸状态的偶极矩。
DOI：
10.1021/jp061924x
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发表时间：
2006
期刊：
影响因子：
--
通讯作者：
R. Field
中科院分区：
文献类型：
--
作者：
Bryan M. Wong;A. Steeves;R. Field
用一维局部弯曲模型描述了乙炔在振动能级上的电子性质变化，这些振动能级体现了S0势能面上的大振幅局部运动。在CCSD(T)和MR-AQCC理论水平上进行的计算预测了偶极矩与局部弯曲或局部拉伸激发中的量子数的近似线性依赖关系。在本地模式下极限,一个量子的拉伸激发CH债券导致增加了0.025 D的偶极矩,和一个量子CCH的弯曲振动角会导致增加了0.068 D局部弯曲使用一维模型是合理的,通过比较完善的polyad模型,揭示了一个解耦的大型振幅从其他自由度弯曲Nbend = 14-22的范围。我们发现相同的一维大振幅弯曲运动出现在两种截然不同的表示中，一种是通过从头算的一维切割，七维哈密顿量和三维（l = 0）纯弯曲实验参数化光谱哈密顿量。
A one-dimensional local bend model is used to describe the variation of electronic properties of acetylene in vibrational levels that embody large amplitude local motions on the S0 potential energy surface. Calculations performed at the CCSD(T) and MR-AQCC levels of theory predict an approximately linear dependence of the dipole moment on the number of quanta in either the local bending or local stretching excitation. In the local mode limit, one quantum of stretching excitation in one CH bond leads to an increase of 0.025 D in the dipole moment, and one quantum of bending vibration in the CCH angle leads to an increase of 0.068 D. The use of a one-dimensional model for the local bend is justified by comparison to the well-established polyad model which reveals a decoupling of the large amplitude bending from other degrees of freedom in the range of Nbend = 14-22. We find that the same one-dimensional large amplitude bending motion emerges from two profoundly different representations, a one-dimensional cut through an ab initio, seven-dimensional Hamiltonian and the three-dimensional (l = 0) pure-bending experimentally parametrized spectroscopic Hamiltonian.