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Development of generation of large-male potential energy surfaces num local interpolation and molecular mechanics

大雄势能面num局部插值和分子力学生成的发展

基本信息

批准号：
16550025
负责人：
ISHIDA Toshimasa
金额：
$ 2.16万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2007
项目状态：
已结题

项目摘要

In large scale systems, so called QM/MM methods have been employed in the quantum chemistry society and tens of trajectories (even only one trajectory) sometimes have been employed to extract the picture of reaction mechanism. However, it is still difficult for us to obtain the number of trajectories which is statistically significant because potential energy calculations are time consuming. The statistically significant result may be drastically different from the picture that was obtained from tens of trajectory calculations. Thus, it is desirable to construct a method to evaluate potential energy surface fast. We attempted to combine a local interpolation scheme, IMLS/Shepard scheme, and molecular mechanics, but the attempt is still under way.Thus, we have undertaken a direct dynamics for a biomolecule, retinal, instead. We described the dynamics of retinal using Zhu-Nakamura formula for non-adiabatic transitions from the first (photo) exited state to the ground state. We treated all the degrees of freedom in our direct dynamics although we originally planned to describe small number of degrees of freedom icing IMLS/Shepard scheme and the other degrees of freedom using molecular mechanics. We have found that retinal (at least in gas phase) experiences two-step relaxation after the deexcitation through non-adiabatic transition.Also, we have applied our IMLS/Shepard scheme to the O+HCl system. Large scale trajectory calculations using three potential energy surfaces have been carried out to obtain reactive differential cross sections and the results are in agreement with experiment We have found that the dynamics is determined by that in the ground state although the two excited states are in a relatively low energy region.

在大尺度体系中，量子化学学会采用了所谓的QM/MM方法，有时用几十条轨迹（甚至一条轨迹）来提取反应机理图。然而，我们仍然很难获得的轨迹的数量是统计上显着的，因为势能计算是耗时的。统计上显著的结果可能与从数十个轨迹计算获得的图片截然不同。因此，需要建立一种快速计算势能面的方法。我们尝试将局部插值方案、IMLS/谢泼德方案和分子力学结合起来，但这一尝试仍在进行中，因此，我们对生物分子视网膜进行了直接动力学研究。我们用Zhu-Nakamura公式描述了视网膜从第一激发态到基态的非绝热跃迁动力学。虽然我们最初计划用分子力学来描述少量的结冰IMLS/谢泼德方案和其他自由度，但我们在直接动力学中处理了所有的自由度。我们发现，至少在气相中，Retinal在去激发后经历了两步弛豫，并将IMLS/谢泼德方案应用于O+HCl体系。用三个势能面进行了大尺度轨道计算，得到了与实验相符的反应微分截面。发现虽然两个激发态处于较低能区，但动力学仍由基态动力学决定。