量子振动微扰方法的发展及其在氯化氢—水团簇与丙酮水溶液中的应用

发布时间：2018-06-01 06:22

本文选题：探针分子 + 线性/二维红外光谱　；参考：《吉林大学》2017年硕士论文

【摘要】：将分子的某个特殊位点作为探针来研究其振子所处环境的一维和二维红外光谱对在分子层面上理解在凝聚相以及生物体系中的局域氢键网络,组态动力学以及长程静电相互作用都有特殊意义。然而,到目前为止,由于超快的时间尺度、核的量子效应以及大尺度分子处于复杂的环境中等原因,导致对于实验光谱的量子解释仍然是一个巨大的挑战。为实现这个目标,其中一个重要的困难是计算时间依赖的振动跃迁频率,并且这个频率的计算得包含振动运动的量子效应。在我的这个工作中,我们提出了一种快速并且精确的新方法来重现一维和二维的红外光谱——量子振动微扰(Quantum Vibrational Perturbation,QVP)。该方法主要是为了提升计算分子中生色基团的瞬时量子振动频率的精度和效率。该方法是将经典取样和利用量子力学获得某一特殊振动模的跃迁频率相结合的一种半经典的方法。经典取样主要是利用经典的从头算分子动力学来获得分子间的构型密度分布,而这里的量子效应主要是通过一阶微扰近似来将量子效应包含在振动跃迁频率的计算中。用离散变分格点的方法来描述振动基态与激发态的波函数,使得计算的效率大大地提高,而微扰方法是用来获得由于溶剂环境涨落而导致的振动频率位移,同时其也避免了解薛定谔方程,提高了振动频率获得的效率。量子力学/分子力学联合势能将用于对溶液环境的模拟,其也将大大降低了分子动力学势能的计算,进而使得该方法在大生物蛋白分子中的应用成为可能。我们发现一阶微扰,对于该计算已经足够精确了,进而获得基于从头算分子动力学轨迹的振动频率。本文同时也提出了量子振动微扰方法在氯化氢-水团簇以及在丙酮水溶液中的应用,并且分别得到了在氯化氢-水团簇体系中的氯氢伸缩振动的一维和二维红外光谱以及丙酮水溶液中的羰基伸缩振动的一维红外光谱。为了进一步降低计算成本,我们提出了一种杂化的策略,并且我们发现通过该策略计算得到的峰的位置和形状都与实验结果符合地非常好。另外,我们发现了在氯氢伸缩振动模中,非谐效应起到了重要的作用,而氢键相互作用加剧了这种非谐效应。
[Abstract]:A special site of the molecule is used as a probe to study the local hydrogen bond network in the condensed phase and in the biological system at the molecular level. Configuration dynamics and long-range electrostatic interaction are of special significance. However, the quantum interpretation of experimental spectra is still a great challenge due to the ultrafast time scale, the quantum effects of nuclei and the large scale molecules in complex environments. In order to achieve this goal, one of the important difficulties is to calculate the time-dependent vibration transition frequency, and the calculation of this frequency includes the quantum effect of vibration motion. In my work, we propose a fast and accurate new method to reproduce the quantum Vibrational perturbation QVPs of one and two dimensional infrared spectra, Quantum Vibrational Perturation, Quantum Vibrational Perturation, Quantum Vibrational Perturation, Quantum Vibrational Perturation, Quantum Vibrational Perturation, and Quantum Vibrational Perturation. The main purpose of this method is to improve the accuracy and efficiency of calculating the instantaneous quantum vibration frequency of chromophore groups in molecules. This method is a semiclassical method which combines classical sampling with obtaining the transition frequency of a special vibration mode by quantum mechanics. Classical sampling mainly uses the classical ab initio molecular dynamics to obtain the density distribution of the intermolecular configuration, and the quantum effect is mainly included in the calculation of the vibrational transition frequency by the first-order perturbation approximation. The method of discrete variational lattice points is used to describe the wave functions of the ground and excited states of vibration. The efficiency of calculation is greatly improved, while the perturbation method is used to obtain the vibration frequency displacement caused by the fluctuation of the solvent environment. At the same time, it avoids the understanding of Schrodinger equation and improves the efficiency of vibration frequency. The combined potential energy of quantum mechanics and molecular mechanics will be used to simulate the solution environment, which will greatly reduce the calculation of molecular dynamics potential energy. We find that the first order perturbation is accurate enough for this calculation, and then the vibration frequency based on ab initio molecular dynamics locus is obtained. At the same time, the application of quantum vibration perturbation method in hydrogen chloride water cluster and acetone aqueous solution is also presented. The one dimensional and two dimensional infrared spectra of the stretching vibration of hydrogen chloride and water cluster system and the one dimensional infrared spectrum of the stretching vibration of carbonyl group in acetone aqueous solution were obtained respectively. In order to further reduce the computational cost, we propose a hybrid strategy, and we find that the position and shape of the calculated peaks are in good agreement with the experimental results. In addition, we find that the anharmonic effect plays an important role in the chlorohydrogen stretching vibration mode, and the hydrogen bond interaction intensifies the anharmonic effect.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O645.1

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