Simulation of Chemical Reactions in Solution With the Combined Quantum Mechanical and Molecular Mechanical Potential

高牢狱由理论与计算化学项目资助，在溶液中进行化学反应的计算机模拟。一种结合量子力学和分子力学的方法，将从头算Hartree-Fock和分子轨道技术与统计力学蒙特卡罗模拟相结合，用于研究非常简单的化学物质在溶液中的化学反应。对更复杂的化学物质的类似计算将采用半经验哈密顿量，如AM1和INDO/S，并结合蒙特卡罗模拟技术。研究的反应包括3-羧基苯并异恶唑的脱羧反应和水溶液中氯化丁酯的电离反应。除了研究溶液中的化学反应外，溶剂对发色团电子吸收光谱的影响也将使用相同的模型进行研究。溶液中化学反应的计算机模拟提供了影响反应速率因素的重要分子水平的见解。特别是溶剂化和伴随的极化对降低化学反应障碍的具体贡献可以进行详细的研究。然而，许多更有趣的断键反应表现出量子效应，不能用经验势有效地建模。Gao的方法包括使用一种联合模拟方法，该方法使用蒙特卡罗和分子轨道理论来处理化学反应过程中发生变化的量子自由度。

Jaili Gao is funded by a grant from the Theoretical and Computational Chemistry Program to perform computer simulations of chemical reactions in solution. A combined quantum mechanical and molecular mechanical methodology is being developed which combines ab initio Hartree-Fock and molecular orbital techniques with statistical mechanical Monte Carlo simulations to study chemical reactions in solution for very simple chemical species. Analogous calculations on more complex chemical species will employ semiempirical Hamiltonians such as AM1 and INDO/S in conjunction with Monte Carlo simulation techniques. Reactions to be studied include the decarboxylation of 3-carboxybenzisoxazoles and the ionization of t-butyl chloride in aqueous solution.. In addition to studies of chemical reactions in solution, solvent effects on electronic absorption spectra of chromophores will be examined using the same model. Computer simulations of chemical reactions in solution provide important molecular level insights into the factors which influence reaction rates. In particular specific contributions which solvation and accompanying polarization make to lowering barriers to chemical reaction can be studied in detail. Many of the more interesting bond breaking reactions, however, exhibit quantum effects which cannot be modeled effectively using empirical potentials. Gao's approach involves the use of a combined simulation approach which uses Monte Carlo and molecular orbital theory to treat the quantum degrees of freedom undergoing change during the chemical reaction.