University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Institute for Molecular Science, Myodaiji, Okazaki, Aichi 444-8585, Japan and The Graduate University for Advanced Studies, Myodaiji, Okazaki, Aichi 444-8585, Japan.
J Chem Phys. 2019 Mar 14;150(10):100901. doi: 10.1063/1.5083966.
Two-dimensional (2D) vibrational spectroscopy has emerged as one of the most important experimental techniques useful to study the molecular structure and dynamics in condensed phases. Theory and computation have also played essential and integral roles in its development through the nonlinear optical response theory and computational methods such as molecular dynamics (MD) simulations and electronic structure calculations. In this article, we present the fundamental theory of coherent 2D vibrational spectroscopy and describe computational approaches to simulate the 2D vibrational spectra. The classical approximation to the quantum mechanical nonlinear response function is invoked from the outset. It is shown that the third-order response function can be evaluated in that classical limit by using equilibrium or non-equilibrium MD simulation trajectories. Another simulation method is based on the assumptions that the molecular vibrations can still be described quantum mechanically and that the relevant molecular response functions are evaluated by the numerical integration of the Schrödinger equation. A few application examples are presented to help the researchers in this and related areas to understand the fundamental principles and to use these methods for their studies with 2D vibrational spectroscopic techniques. In summary, this exposition provides an overview of current theoretical efforts to understand the 2D vibrational spectra and an outlook for future developments.
二维（2D）振动光谱已成为研究凝聚相分子结构和动力学最重要的实验技术之一。通过非线性光学响应理论和计算方法，如分子动力学（MD）模拟和电子结构计算，理论和计算在其发展中也发挥了至关重要的作用。在本文中，我们介绍了相干 2D 振动光谱的基本理论，并描述了模拟 2D 振动光谱的计算方法。从一开始就调用了量子力学非线性响应函数的经典近似。结果表明，可以通过使用平衡或非平衡 MD 模拟轨迹在该经典极限中评估三阶响应函数。另一种模拟方法基于以下假设：分子振动仍然可以用量子力学来描述，并且通过数值求解薛定谔方程来评估相关的分子响应函数。本文提供了一些应用示例，以帮助该领域和相关领域的研究人员理解基本原理，并使用这些方法进行 2D 振动光谱技术研究。总之，本文对当前理解 2D 振动光谱的理论研究进展进行了综述，并对未来的发展进行了展望。
