中文摘要：

采用CCSD（T）//B3LYP/6-311＋G（d,p）方法研究了Criegee中间体CH_3CHOO与OH自由基反应的微观机理.结果表明,上述反应存在抽氢、加成-分解和氧化3类反应通道,其中,syn-CH3CHOO＋OH以抽β-H为优势通道,表观活化能为-4.88 k J/mol;anti-CH_3CHOO＋OH则以加成-分解反应为优势通道,表观活化能为-13.25 k J/mol.在加成-分解和氧化反应通道中,anti-构象的能垒均低于syn-构象,而抽氢反应则是syn-（β-H）的能垒低于anti-构象.速率常数计算表明,anti-构象的加成-分解反应通道具有显著的负温度效应;syn-和anti-构象的氧化通道具有显著的正温度效应.3类反应具有显著不同的温度效应,说明通过改变温度可显著调节3类反应的相对速率.

英文摘要：

The reaction mechanism of CH_3CHOO with OH was studied at the CCSD（ T） / / B3 LYP / 6-311 ＋G（ d,p） level. The results show that the detailed mechanism mainly includes hydrogen abstraction,additiondecomposition and oxidation reactions. The calculations show that β-H abstraction reaction is favoured in the syn-CH3CHOO reaction with OH with a apparent activation energy（ Eapp） of-4. 88 k J/mol,whereas the addition-decomposition channel is advantaged in the reaction of anti-CH3CHOO with OH in combination with a Eappof-13. 25 k J / mol. The barriers of anti-CH3 CHOO are lower than that of the syn-CH3CHOO in additiondecomposition and oxidation reactions,while the syn-CH3 CHOO is lower than anti-CH3CHOO in the β-H abstraction pathway. The rate constant of addition-decomposition in the reaction of anti-CH3 CHOO satisfies a strong negative temperature dependent,while oxidation channels of syn-/ anti-CH3CHOO obey a positive temperature effect. The temperature dependent of three kind of reactions are different,which makes their relative rate can be controlled by adjusting the temperature.