International Research Fellowship Program: Chemical Reactions Involving Multiple Electronic States

0401585 Netzloff国际研究奖学金计划使美国科学家和工程师能够在国外进行三到二十四个月的研究。该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。该奖项将支持由博士石楠M二十二个月的研究奖学金。Netzloff与Michael A.柯林斯在澳大利亚堪培拉的澳大利亚国立大学。该项目旨在开发方法和程序，研究在多个电子状态下通过分子动力学发生的化学反应。许多化学反应在分子处于基态时发生。原子的运动受单个分子势能面（PES）控制。然而，许多重要的化学反应，从大气化学到有机和无机化学中的光化学反应机制，再到光合作用等基本生物现象，都是通过一种以上的电子状态的动力学发生的。在过去的几年里，Michael柯林斯博士和同事们开发了一种自动化的方法来构建一个PES，然后在一个名为GROW的程序包中研究PES上的反应动力学。最近的一项合作涉及柯林斯博士，马克戈登博士和收件人，导致了部分接口的生长与从头算量子化学程序，GAMESS。在此接口之前，GROW是不能够构建一个PES时，激发电子状态接近基态。能量相近的多电子态只能通过所谓的多参考方法，特别是多组态自洽场（MCSCF）方法可靠地计算。MCSCF波函数的高效计算是GAMESS的标志性功能之一。这个博士后奖学金使得有可能极大地扩展GAMESS-GROW接口的能力，以提供研究激发电子状态下的化学反应和通过多个电子状态进行的反应的手段。在Grow-GAMESS界面中包含MCSCF计算使得可以生长多参考PES。该项目的第一个重要成果将是对所谓的“导数耦合”进行有效评估的推导和编码，该耦合将核运动与电子波函数耦合到GAMESS中。这将首先完成MCSCF波函数，随后在更高层次的理论。一个有效的GAMESS-GROW接口将提供有效地构建全局多PES和耦合表面，管理化学反应的手段。这些工具的应用将允许重要的自由基反应的动力学研究，以前不能与从头计算表面研究。最初的重点将放在OH和CH自由基的反应上，它们在燃烧化学、地球和其他行星大气的化学以及星际化学中发挥着重要作用。

0401585NetzloffThe International Research Fellowship Program enables U.S. scientists and engineers to conduct three to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-two-month research fellowship by Dr. Heather M. Netzloff to work with Dr. Michael A. Collins at Australian National University in Canberra, Australia.This project aims to develop methods and programs to study chemical reactions that occur by molecular dynamics in multiple electronic states. Many chemical reactions occur while the molecule remains in the ground electronic state. The motion of the atoms is governed by a single molecular potential energy surface (PES). However, many important chemical reactions, ranging from atmospheric chemistry to photochemical reaction mechanisms in organic and inorganic chemistry to fundamental biological phenomena such as photosynthesis, take place via dynamics on more than one electronic state. Over the last several years, Dr. Michael Collins and co-workers have developed an automated method to construct a single PES and to then study the dynamics of reactions on the PES in a program package called GROW. A recent collaboration involving Dr. Collins, Dr. Mark Gordon, and the recipient, resulted in the partial interface of GROW with the ab initio quantum chemistry program, GAMESS. Before this interface, GROW was not capable of constructing a PES when excited electronic states are close to the ground state. Multiple electronic states, close in energy, can only be reliably calculated by using so-called multi-reference methods, in particular multi-configuration self consistent field (MCSCF) approaches. The efficient computation of MCSCF wavefunctions is one of GAMESS' hallmark capabilities. This postdoctoral fellowship is making it possible to enormously expand the power of the GAMESS-GROW interface to provide the means to study chemical reactions in excited electronic states and reactions which proceed via multiple electronic states. The inclusion of MCSCF calculations within the Grow-GAMESS interface makes it possible to grow multi-reference PESs. By itself, this opens up a wide range of new, important applicationsThe first important outcome of the project will be the derivation and coding of the efficient evaluation of the so-called "derivative coupling" that couples nuclear motion with the electronic wavefunction into GAMESS. This will initially be accomplished for MCSCF wavefunctions and subsequently at higher levels of theory. An effective GAMESS-GROW interface will provide the means for efficiently constructing the global multiple PESs and coupling surfaces that govern chemical reactions. Application of these tools will allow the study of the dynamics of important radical reactions that previously could not be studied with ab initio surfaces. The initial focus will be on the reactions of OH and CH radicals, which play important roles in combustion chemistry, in the chemistry of Earth's and other planetary atmospheres, and in interstellar chemistry.