Full quantum mechanical modeling of protonated water clusters

在过去的两年里，我们已经取得了非常实质性的进展，对两个主要的工作包设置为最初的建议：（1）自动和动态确定最佳树结构的上下文中的多层多构型的时间依赖Hartree方法;（2）全量子力学建模的光谱和动力学的扩展Zundel（EZ）阳离子。后者已经在全维（51 D）中使用多球坐标和精确的动能算子进行了描述，并在D.马克思（U.波鸿）。 具体来说，我们已经开发和实现了波函数张量树的自动构建工具，我们已经能够计算出高质量的EZ系统的红外光谱。扩展项目的主要目的仍然是通过基于动态张量网络和多构型时间依赖Hartree Ancillary的新方法发展，推动灵活和高度相关分子和团簇的全量子动力学描述的界限，并将其应用于气相和溶液中EZ阳离子的全量子力学描述。我们在理想的方向上取得了很大进展。（2.1）详细研究Zundel谱和EZ谱之间的联系，从量子力学的角度全面理解过剩质子的微溶剂化。(2.2)我们计划研究嵌入的EZ阳离子从模拟环境中获得的外部字段，从而采取一定的步骤，对一个完整的量子表征的溶剂化质子在溶液中。在这些领域的进展将是重要的溶剂化质子，质子化水簇，质子中继网络完全量子力学的进一步理解。通过该项目的方法学发展，我们正在推动最先进的技术，并使大型灵活系统的全量子模拟超越当前的能力。最后但并非最不重要的是，所有的开发都通过全球使用的海德堡MCTDH软件包立即提供给社区。

Over the past two years we have made very substantial progress towards the two main work packages set for the initial proposal: (1) automatic and on-the-fly determination of optimal tree structures in the context of the multi-layer multi-configurational time-dependent Hartree method; (2) full quantum mechanical modeling of the spectroscopy and dynamics of the extended Zundel (EZ) cation. The latter has been described in full dimensionality (51 D) using polyspherical coordinates and an exact kinetic energy operator, and on a very accurate neural-network potential energy surface provided by the group of Prof. D. Marx (U. Bochum). Specifically, we have developed and implemented tools for the automatic construction of wavefunction tensor trees, and we have been able to calculate good quality infrared spectra of the EZ system. The main aim of the extension project is still to push the boundaries for the full quantum dynamical description of flexible and highly correlated molecules and clusters through new methodological developments based on dynamical tensor-networks and the multi-configuration time-dependent Hartree Ansatz and to apply them to the full quantum mechanical description of the EZ cation in the gas phase and in solution. We have come a long way in the desired direction. In the extension period weplan to: (2.1) study in detail the connection between the Zundel and EZ spectra, and from this understand the microsolvation of the excess proton fully quantum-mecanically. (2.2) We plan to study the embedding of the EZ cation in external fields obtained from simulated environments, and thus take definite steps towards a full quantum characterization of the solvated proton in solution. Advancement in those areas will be important for the further understanding of solvated protons, protonated water clusters, and proton-relay networks fully quantum mechanically. Through the methodological developments of this project, we are pushing the state-of-the-art and enabling the full quantum simulation of large and flexible systems beyond current capabilities. Last but not least, all developments are being made immediately available to the community through the worldwide used Heidelberg MCTDH software package.