Using Diffusion Monte Carlo Wave Functions to Analyze the Vibrational Spectra of H 7 O 3 + and H 9 O 4 +
Using Diffusion Monte Carlo Wave Functions to Analyze the Vibrational Spectra of H 7 O 3 + and H 9 O 4 +
复制标题
使用扩散蒙特卡罗波函数分析 H 7 O 3 和 H 9 O 4 的振动谱
DOI：
10.1021/acs.jpca.1c05025
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
McCoy, Anne B.
中科院分区：
文献类型：
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作者：
DiRisio, Ryan J.;Finney, Jacob M.;Dzugan, Laura C.;Madison, Lindsey R.;McCoy, Anne B.
从扩散蒙特卡罗（DMC）模拟得到的基态概率幅（GSPA）的光谱评估的方法进行了扩展，以提高激发态能量的描述，并允许振动激发态之间的耦合。这种方法适用于质子化水的三聚体和四聚体，以及它们的氘代类似物的研究。这些离子提供了溶剂化水合氢离子的模型，这些光谱的分析提供了在水环境中质子转移的光谱特征的见解。在这种方法中，我们得到一个可分离的一组内部坐标从DMC基态概率振幅。一个基础，然后开发产品的DMC基态波函数和低阶多项式在这些内部坐标。这种方法提供了一个紧凑的基础，其中的哈密顿量和偶极矩矩阵进行评估，并用于获得频谱。所得光谱与实验结果吻合良好，在许多情况下，与使用大得多的基组获得的结果具有可比性。此外，紧凑的基础允许解释的光谱特征，以及它们如何演变与集群的大小和氘。
An approach for evaluating spectra from ground state probability amplitudes (GSPA) obtained from diffusion Monte Carlo (DMC) simulations is extended to improve the description of excited state energies and allow for coupling among vibrational excited states. This approach is applied to studies of the protonated water trimer and tetramer, and their deuterated analogs. These ions provide models for solvated hydronium, and analysis of these spectra provides insights into spectral signatures of proton transfer in aqueous environments. In this approach, we obtain a separable set of internal coordinates from the DMC ground state probability amplitude. A basis is then developed from products of the DMC ground state wave function and low-order polynomials in these internal coordinates. This approach provides a compact basis in which the Hamiltonian and dipole moment matrix are evaluated and used to obtain the spectrum. The resulting spectra are in good agreement with experiment and in many cases provide comparable agreement to the results obtained using much larger basis sets. In addition, the compact basis allows for interpretation of the spectral features and how they evolve with cluster size and deuteration.