We numerically investigate the quantum dynamics of the high-dimensional rhodopsin photoisomerization models of Hahn and Stock using the multi-layer multi-configuration time-dependent Hartree (ML-MCTDH) method. The original two-state two-mode model is augmented with additional Raman-active modes observed experimentally and by a bath of low frequency modes that accounts in a generic fashion for the effect the protein and solvent environment. A previously used approximate method in which the two primary modes are treated using an accurate quantum dynamical method while the secondary modes are treated using the time-dependent Hartree (TDH) method is tested against ML-MCTDH calculations. It is shown that the former method does not capture the main effect of these modes on the electronic populations, on the coherent torsional dynamics and on the quantum yield of the photoisomerization reaction. Our ML-MCTDH calculations predict small photoisomerization quantum yields, in contradiction with the experiments, and call for a revision of the model.

我们使用多层多组态时变哈特里（ML-MCTDH）方法，对哈恩和斯托克（Hahn）和斯托克（Stock）的高维视紫红质光异构化模型的量子动力学进行了数值研究。原始的两态两模式模型通过实验观察到的其他拉曼活性模式以及一系列低频模式得以增强，这些模式以通用方式解释了蛋白质和溶剂环境的影响。针对ML-MCTDH计算，测试了一种先前使用的近似方法，其中使用精确的量子动力学方法处理了两个主要模式，而使用依赖于时间的Hartree（TDH）方法处理了次要模式。结果表明，前一种方法不能捕获这些模式对电子种群的主要影响，相干扭转动力学和光异构化反应的量子产率。与实验相反，我们的ML-MCTDH计算可预测较小的光异构化量子产率，并要求对该模型进行修订。