Chemistry and Chemical Biology, University of California Merced, Merced, California 95343, USA.
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331, USA.
J Chem Phys. 2021 Feb 28;154(8):084116. doi: 10.1063/5.0038196.
Accurately simulating the linear and nonlinear electronic spectra of condensed phase systems and accounting for all physical phenomena contributing to spectral line shapes presents a significant challenge. Vibronic transitions can be captured through a harmonic model generated from the normal modes of a chromophore, but it is challenging to also include the effects of specific chromophore-environment interactions within such a model. We work to overcome this limitation by combining approaches to account for both explicit environment interactions and vibronic couplings for simulating both linear and nonlinear optical spectra. We present and show results for three approaches of varying computational cost for combining ensemble sampling of chromophore-environment configurations with Franck-Condon line shapes for simulating linear spectra. We present two analogous approaches for nonlinear spectra. Simulated absorption spectra and two-dimensional electronic spectra (2DES) are presented for the Nile red chromophore in different solvent environments. Employing an average Franck-Condon or 2DES line shape appears to be a promising method for simulating linear and nonlinear spectroscopy for a chromophore in the condensed phase.
准确模拟凝聚相系统的线性和非线性电子光谱，并考虑对光谱线形状有贡献的所有物理现象，这是一个巨大的挑战。通过从发色团的正则模态生成的谐波模型可以捕获振子跃迁，但在这种模型中也包括特定发色团-环境相互作用的影响是具有挑战性的。我们通过结合方法来克服这一限制，这些方法可以同时考虑明确的环境相互作用和振子耦合，以模拟线性和非线性光学光谱。我们提出并展示了三种不同计算成本的方法，用于结合发色团-环境构型的集合采样与模拟线性光谱的 Franck-Condon 线形状。我们提出了两种类似的非线性光谱方法。在不同的溶剂环境中，展示了尼罗红发色团的吸收光谱和二维电子光谱（2DES）。对于凝聚相中的发色团，采用平均 Franck-Condon 或 2DES 线形状似乎是模拟线性和非线性光谱的一种很有前途的方法。
