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多肽对红外激光脉冲的非线性响应中包含了丰富的结构动力学信息。本文以肽链的酰胺振动跃迁为例,提出了模拟二维红外相干光谱的理论方案。文中首先介绍了激子模型下非线性响应的微扰图像,并基于激子模型、经典分子动力学模拟和密度泛函静电势,构建酰胺振动模式有效波动哈密顿量。采用随机刘维尔方程(SLE)、数值演化(NP)、高斯波动的累积展开(CGF)等方法计算非线性响应光谱。文章最后对多肽及多肽复合物等体系的二维红外信号进行模拟和讨论。
The non-linear response of peptides to infrared laser pulses contains a wealth of structural kinetic information. In this paper, taking the vibrational transition of amide chain as an example, a theoretical scheme of simulating two-dimensional infrared coherence spectroscopy is proposed. Firstly, the perturbation image of nonlinear response in exciton model is introduced. Based on the exciton model, classical molecular dynamics simulation and the density functional electrostatic potential, an effective oscillation Hamiltonian of amide vibration mode is constructed. Nonlinear response spectra were calculated using the random Liuvelle equation (SLE), numerical evolution (NP), and cumulative expansion of Gaussian fluctuations (CGF). Finally, the article simulates and discusses the two-dimensional infrared signals of polypeptide and polypeptide complexes.