Institute of Physics, Rostock University, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany.
J Chem Phys. 2018 Mar 14;148(10):102337. doi: 10.1063/1.5011764.
The framework to approach quasi-classical dynamics in the electronic ground state is well established and is based on the Kubo-transformed time correlation function (TCF), being the most classical-like quantum TCF. Here we discuss whether the choice of the Kubo-transformed TCF as a starting point for simulating vibronic spectra is as unambiguous as it is for vibrational ones. Employing imaginary-time path integral techniques in combination with the interaction representation allowed us to formulate a method for simulating vibronic spectra in the adiabatic regime that takes nuclear quantum effects and dynamics on multiple potential energy surfaces into account. Further, a generalized quantum TCF is proposed that contains many well-established TCFs, including the Kubo one, as particular cases. Importantly, it also provides a framework to construct new quantum TCFs. Applying the developed methodology to the generalized TCF leads to a plethora of simulation protocols, which are based on the well-known TCFs as well as on new ones. Their performance is investigated on 1D anharmonic model systems at finite temperatures. It is shown that the protocols based on the new TCFs may lead to superior results with respect to those based on the common ones. The strategies to find the optimal approach are discussed.
在电子基态中研究准经典动力学的框架已经建立，其基础是 Kubo 变换后的时间相关函数（TCF），这是最具经典特征的量子 TCF。在这里，我们讨论了将 Kubo 变换后的 TCF 作为模拟振子光谱的起点是否像对振动光谱那样明确。我们采用虚时间路径积分技术结合相互作用表象，提出了一种在绝热条件下模拟振子光谱的方法，该方法考虑了核量子效应和多个势能面上的动力学。此外，我们还提出了一种广义量子 TCF，它包含许多成熟的 TCF，包括 Kubo TCF 作为特例。重要的是，它还为构建新的量子 TCF 提供了一个框架。将开发的方法应用于广义 TCF 会导致大量的模拟方案，这些方案基于著名的 TCF 和新的 TCF。在有限温度下，我们对一维非谐模型系统进行了研究。结果表明，基于新 TCF 的方案可能会得到比基于常见 TCF 的方案更好的结果。我们讨论了寻找最佳方法的策略。
