Development of Programs for Reaction Path Following and Spin Projection

在化学系理论与计算项目的这个项目中，Schlegel教授将开发新的算法来跟踪分子势能表面上的反应路径。PI使用这些计算工具来研究含有硅、氢和氟的分子的热力学和反应性，这些分子与用于光伏的非晶硅薄膜的化学气相沉积和用于微电子的硅表面的蚀刻有关。提出了一种新的反应路径跟踪算法。先前开发的用于基态波函数相关校正的自旋投影方法将得到扩展，自旋投影将用于激发态的CI单次计算（基态决定函数的单次替换）。将开发一种新的过渡结构优化算法和一种新型的电场依赖基础来计算改进的偶极矩、极化率和红外强度。在应用方面，将探讨简单光化学反应的机理。反应路径跟踪将用于研究溶剂分子对SN2反应过渡态的影响。过渡结构和势垒高度将决定自由基抽象，自由基加成到多个键和双自由基环加成反应。对硅化合物热分解的研究将继续进行。

In this project in the Theoretical and Computational Program of the Chemistry Division, Professor Schlegel will develop new algorithms for reaction path following on molecular potential energy surfaces. The PI uses these computational tools to study the thermodynamics and reactivity of molecules containing silicon, hydrogen and flourine that are relevant to chemical vapor deposition of amorphous silicon films for photovoltaics and etching of silicon surfaces for microelectronics. A family of five new reaction path following algorithms is proposed. Previously developed spin projection methods for correlation corrections to ground state wave functions will be extended and spin projections will be developed for CI singles calculations (single substitutions in the ground state determinantal function) of excited states. A new transition structure optimization algorithm and a new type of electric field dependent basis to calculate improved dipole moments, polarizability and infrared intensities will be developed. In the area of applications the mechanism of simple photochemical reactions will be explored. Reaction path following will be used to study the effect of solvent molecules on transition states for SN2 reactions. Transition structures and barrier heights will be determined for radical abstractions, radical additions to multiple bonds and diradical cycloaddition reactions. The study of the thermal decomposition of silicon compounds will be continued.