Extension of the effective relativistic coupling by asymptotic representation (ERCAR) approach to multi-dimensional potential energy surfaces: 3D model for CH3I
Extension of the effective relativistic coupling by asymptotic representation (ERCAR) approach to multi-dimensional potential energy surfaces: 3D model for CH3I
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DOI：
10.1063/1.5011757
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发表时间：
2018-03
影响因子：
4.4
通讯作者：
Nils Wittenbrink;W. Eisfeld
中科院分区：
文献类型：
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作者：
Nils Wittenbrink;W. Eisfeld
有效相对论耦合渐近表示（Effective Relativistic Coupling by Asymptotic Representation，ERCAR）方法是我们在过去几年中发展起来的一种新方法，它允许精确的非绝热表示分子的库仑和自旋轨道哈密顿量，并产生用于量子动力学模拟的解析势能面（PES）模型。到目前为止，我们关注的是定义非绝热表象渐近线的单个解离坐标，对应于从剩余碎片中移除单个强相对论性原子。在本研究中，我们首次将这种方法扩展到多个维度。为此，一个三维PES模型开发的甲基碘（CH 3 I）系统占所有完全对称的坐标（C-I拉伸，CH 3伞，CH 3呼吸模式）。模型参数拟合相对于高级别从头计算参考数据的自旋空间（“自旋自由”）的状态，这是非常好的精度再现。ERCAR方法也产生了…
The Effective Relativistic Coupling by Asymptotic Representation (ERCAR) approach is a new method developed by us over the past few years that allows for the accurate diabatic representation of a molecular Coulomb and spin-orbit Hamiltonian and yields an analytic potential energy surface (PES) model for use in quantum dynamics simulations. So far, we focused on the single one dissociation coordinate defining the asymptote for diabatic representation and corresponding to removing a single, strongly relativistic atom from the remaining fragment. In the present study, we extend this approach to multiple dimensions for the first time. To this end, a 3D PES model is developed for the methyl iodide (CH3I) system accounting for all totally symmetric coordinates (C–I stretch, CH3 umbrella, and CH3 breathing modes). The model parameters are fitted with respect to high-level ab initio reference data for the spin space (“spin-free”) states which are reproduced with very good accuracy. The ERCAR method also yields th...