Farantos Stavros C
Institute of Electronic Structure and Laser, Foundation for Research and Technology-Hellas, Iraklion 71110, Crete, Greece.
J Chem Phys. 2007 May 7;126(17):175101. doi: 10.1063/1.2727471.
Small and large molecules may localize their energy in specific bonds or generally in vibrational modes for extended periods of time, an effect which may have dramatic consequences in reaction dynamics. Periodic orbits offer the means to identify phase space regions with localized motions. The author demonstrate that techniques to locate periodic orbits developed for small molecules can be applied to large molecules such as alanine dipeptide. The widely used empirical force fields are employed and principal families of periodic orbits associated with local-type motions and emanated from the lowest energy minima and saddle points are investigated. Continuation of these families at high energies unravels the stable and unstable regions of phase space as well as elementary bifurcations such as saddle nodes.
小分子和大分子可能会在特定化学键中或通常在振动模式下长时间定位其能量，这种效应可能会在反应动力学中产生显著后果。周期轨道提供了识别具有局域运动的相空间区域的方法。作者证明，为小分子开发的定位周期轨道的技术可以应用于诸如丙氨酸二肽这样的大分子。采用了广泛使用的经验力场，并研究了与局域型运动相关且源自最低能量极小值和鞍点的周期轨道的主要族系。这些族系在高能量下的延续揭示了相空间的稳定和不稳定区域以及诸如鞍结等基本分岔。
