School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
J Chem Phys. 2012 Jun 14;136(22):224102. doi: 10.1063/1.4727853.
Vibrational analysis within a partial Hessian framework can successfully describe the vibrational properties of a variety of systems where the vibrational modes of interest are localized within a specific region of the system. We have developed a new approach to calculating anharmonic frequencies based on vibrational frequencies and normal modes obtained from a partial Hessian analysis using second-order vibrational perturbation theory and the transition optimized shifted Hermite method. This allows anharmonic frequencies for vibrational modes that are spatially localized to be determined at a significantly reduced computational cost. Several molecular systems are examined in order to demonstrate the effectiveness of this method including organic molecules adsorbed on the Si(100)-2×1 surface, model peptides in solution, and the C-H stretching region of polycyclic aromatic hydrocarbons. Overall, for a range of systems, anharmonic frequencies calculated using the partial Hessian approach are found to be in close agreement with the results obtained using full anharmonic calculations while providing a significant reduction in computational cost.
在偏 Hessian 框架内进行振动分析可以成功描述各种系统的振动特性，其中感兴趣的振动模式在系统的特定区域内局部化。我们开发了一种新的方法，基于通过二阶振动微扰理论和跃迁优化的移位 Hermite 方法从偏 Hessian 分析中获得的振动频率和正则模式来计算非谐频率。这允许以显著降低的计算成本确定空间局部化的振动模式的非谐频率。研究了几个分子系统，以证明该方法的有效性，包括吸附在 Si(100)-2×1 表面上的有机分子、溶液中的模型肽以及多环芳烃的 C-H 伸缩区域。总体而言，对于一系列系统，使用偏 Hessian 方法计算的非谐频率与使用全非谐计算获得的结果非常吻合，同时显著降低了计算成本。
