Department of Chemistry, Korea University, Seoul 136-713, South Korea.
J Chem Phys. 2013 May 7;138(17):174108. doi: 10.1063/1.4802991.
The Hessian matrix reconstruction method initially developed to extract the basis mode frequencies, vibrational coupling constants, and transition dipoles of the delocalized amide I, II, and III vibrations of polypeptides and proteins from quantum chemistry calculation results is used to obtain those properties of delocalized O-H stretch modes in liquid water. Considering the water symmetric and asymmetric O-H stretch modes as basis modes, we here develop theoretical models relating vibrational frequencies, transition dipoles, and coupling constants of basis modes to local water configuration and solvent electric potential. Molecular dynamics simulation was performed to generate an ensemble of water configurations that was in turn used to construct vibrational Hamiltonian matrices. Obtaining the eigenvalues and eigenvectors of the matrices and using the time-averaging approximation method, which was developed by the Skinner group, to calculating the vibrational spectra of coupled oscillator systems, we could numerically simulate the O-H stretch IR spectrum of liquid water. The asymmetric line shape and weak shoulder bands were quantitatively reproduced by the present computational procedure based on vibrational exciton model, where the polarization effects on basis mode transition dipoles and inter-mode coupling constants were found to be crucial in quantitatively simulating the vibrational spectra of hydrogen-bond networking liquid water.
希瑟矩阵重构方法最初是为了从量子化学计算结果中提取多肽和蛋白质中非定域酰胺 I、II 和 III 振动的基模频率、振动耦合常数和跃迁偶极子而开发的，现被用于获得液体水中非定域 O-H 伸缩模式的这些性质。考虑到水分子对称和不对称 O-H 伸缩模式作为基模，我们在这里开发了理论模型，将基模的振动频率、跃迁偶极子和耦合常数与局部水分子构型和溶剂电势联系起来。通过分子动力学模拟生成了一组水分子构型，然后用于构建振动哈密顿矩阵。通过使用 Skinner 小组开发的时间平均近似方法来获得矩阵的本征值和本征向量，并计算耦合振荡器系统的振动光谱，我们可以对液体水的 O-H 伸缩 IR 光谱进行数值模拟。本计算程序基于振动激子模型，定量再现了非对称线形状和弱肩带，其中发现极化效应对基模跃迁偶极子和模式间耦合常数的影响对于定量模拟氢键网络液体水的振动光谱至关重要。
