论文标题
凝结相动态的2D光谱学：从平衡多时间相关函数访问三阶响应属性
2D spectroscopies from condensed phase dynamics: Accessing third-order response properties from equilibrium multi-time correlation functions
论文作者
论文摘要
三阶响应是模拟和解释非线性光谱镜的核心，范围从二维红外（2D-IR）到2D电子（2D-ES）和2D总和频率产生（2D-SFG）。这些光谱学中的额外时间和频率尺寸可访问有关存在的电子和振动状态的丰富信息，它们之间的耦合以及它们交换线性光谱中遮盖的能量的产生速率，尤其是对于通常包含许多重叠特征的凝结相系统。尽管已经确定了三阶响应的确切量子表达，但与计算大型冷凝相系统的原子动力学的方法不相容。 These methods, which include both classical mechanics and quantum dynamics methods that retain quantum statistical properties while obeying the symmetries of classical dynamics, such as LSC-IVR, Centroid Molecular Dynamics (CMD) and Ring Polymer Molecular Dynamics (RPMD) naturally provide short-time approximations to the multi-time symmetrized Kubo transformed correlation function.在这里，我们展示了如何以平衡对称的Kubo转换相关函数来制定三阶响应。我们通过展示如何使用经典动力学和RPMD来获得一系列模型系统的三阶响应来证明我们方法的实用性和准确性。特别是，我们表明这种方法捕获了诸如Anharmon诱导的垂直分裂和峰值变化之类的特征，同时提供了一个物理上透明的框架来理解多维光谱镜。
The third-order response lies at the heart of simulating and interpreting nonlinear spectroscopies ranging from two dimensional infrared (2D-IR) to 2D electronic (2D-ES), and 2D sum frequency generation (2D-SFG). The extra time and frequency dimensions in these spectroscopies provides access to rich information on the electronic and vibrational states present, the coupling between them, and the resulting rates at which they exchange energy that are obscured in linear spectroscopy, particularly for condensed phase systems that usually contain many overlapping features. While the exact quantum expression for the third-order response is well established it is incompatible with the methods that are practical for calculating the atomistic dynamics of large condensed phase systems. These methods, which include both classical mechanics and quantum dynamics methods that retain quantum statistical properties while obeying the symmetries of classical dynamics, such as LSC-IVR, Centroid Molecular Dynamics (CMD) and Ring Polymer Molecular Dynamics (RPMD) naturally provide short-time approximations to the multi-time symmetrized Kubo transformed correlation function. Here, we show how the third-order response can be formulated in terms of equilibrium symmetrized Kubo transformed correlation functions. We demonstrate the utility and accuracy of our approach by showing how it can be used to obtain the third-order response of a series of model systems using both classical dynamics and RPMD. In particular, we show that this approach captures features such as anharmonically induced vertical splittings and peak shifts while providing a physically transparent framework for understanding multidimensional spectroscopies.
