Tracking the excited-state time evolution of the visual pigment with multiconfigurational quantum chemistry
Tracking the excited-state time evolution of the visual pigment with multiconfigurational quantum chemistry
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DOI：
10.1073/pnas.0701732104
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发表时间：
2007-05-08
影响因子：
11.1
通讯作者：
Olivucci, Massimo
中科院分区：
文献类型：
--
作者：
Frutos, Luis Manuel;Andruniow, Tadeusz;Olivucci, Massimo
引发视觉的主要事件是视色素视紫红质（Rh）中的视网膜光诱导异构化。在这里，我们使用一个缩放的量子力学/分子力学潜力，再现异构化路径与多构型微扰理论确定遵循牛Rh的激发态演化。对140 fs轨道的分析提供了对电子和几何变化的描述，这些变化使系统准备衰变到基态。这些数据揭示了视网膜骨干的复杂变化，在大约60 fs的延迟下，启动了节省空间的“异步自行车踏板或曲轴”运动，导致在110 fs时间尺度上的圆锥形交叉。结果表明，在衰变时实现的扭曲结构的特征的动量，提供了一个自然的路线走向photoRh结构最近通过使用飞秒受激拉曼光谱解决。
The primary event that initiates vision is the photoinduced isomerization of retinal in the visual pigment rhodopsin (Rh). Here, we use a scaled quantum mechanics/molecular mechanics potential that reproduces the isomerization path determined with multiconfigurational perturbation theory to follow the excited-state evolution of bovine Rh. The analysis of a 140-fs trajectory provides a description of the electronic and geometrical changes that prepare the system for decay to the ground state. The data uncover a complex change of the retinal backbone that, at approximate to 60-fs delay, initiates a space saving "asynchronous bicycle-pedal or crankshaft" motion, leading to a conical intersection on a 110-fs time scale. It is shown that the twisted structure achieved at decay features a momentum that provides a natural route toward the photoRh structure recently resolved by using femtosecond-stimulated Raman spectroscopy.