【作者】 白洪涛；

【导师】 黄旭日；

【作者基本信息】 吉林大学 ， 物理化学， 2005， 博士

【摘要】 本论文利用量子化学计算方法对几种大气化学和燃烧化学中典型的自由基反应机理,进行了系统的理论研究。通过理论计算详细的给出了反应中间体结构、稳定性、反应路径等势能面信息,讨论了可能的反应通道和反应机理,对可能的主要产物进行了预测。为大气化学和燃烧化学中重要的自由基—分子反应模型的建立奠定了基础,并且为实验研究提供了有价值的理论信息。主要贡献如下:1.在B3LYP 和CCSD(T)水平下,深入的研究了反应C2H+3O2 的二重态和四重态反应势能面的剖面图,详细地讨论了反应机理,理论结果与实验给出的反应通道和主要产物相一致。2.在B3LYP、MP2 和CCSD(T)水平下,系统地研究了反应HO2+NO2的单重态以及三重态反应势能面的剖面图。计算结果表明, 此反应历程是复杂的多步反应,反应物的初始化连接方式就有五种。预测了反应机理和最可能的主要产物通道。3.在B3LYP 和CCSD(T)水平下,详细地研究了HO2+C2H2 反应,考虑了二重态和四重态两个反应势能面剖面图。主要反应通道都在二重态势能面中,其中包含了10 种产物,16 种反应中间体,以及26 种过渡态。计算结果与实验给出的反应通道和主要产物相一致。4.为了探寻自由基HO2 在碳氢化合物的燃烧过程的规律和特点,我们还对HO2+C2H 反应进行了研究,在B3LYP 和CCSD(T)水平下给出了比较完整的反应势能面信息,并对主要反应通道和主要产物,次要反应通道和次要产物进行了预测。5.在B3LYP 和CCSD(T)水平下,深入地研究了反应CS+3O2 的单重态以及三重态反应势能面的剖面图。详细地讨论了反应机理,计算结果与实验给出的反应通道和主要产物相符合。6.在B3LYP、MP2 和CCSD(T)水平下,详细地研究了CS+NO 反应,考虑了二重态和四重态两个反应势能面剖面图。预测了反应机理和最可能的主要产物通道。7.在B3LYP 和CCSD(T)水平下,深入的研究了反应CH2+SO,首更多还原

【Abstract】 Recently, the studies on the radical reactions related to combustionchemistry and atmosphere chemistry have been attracting the extensiveattention of some scholars and scientists. Particularly, the experimentalcharacterization and theoretical description of the major products of thereaction and the reaction mechanisms are important topics. The theoreticalinvestigations on the reaction mechanisms of several important radicalreactions related to atmosphere chemistry and combustion chemistry weresystematically carried out. With the computational method, we can not onlyobtain the structures and energies of the intermediate isomers and transitionstates, but also establish a detailed potential energy surface, by means of whichwe can discuss possible reaction channels and reaction mechanisms, and thuspredict the possible major products. Some rules about this kind of radicalreactions have been summarized. The present results can provide theoreticalbasis for understanding the reaction processes and reaction mechanisms ofradical reactions related to atmosphere chemistry and combustion chemistryand for the future experimental measurements. The main results aresummarized as follows.1. The doublet and quartet potential energy surfaces (PES) of reactionC2H+O2 were calculated at the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)level of the theory. The doublet PES shows 9 isomers, 15 transition states, 5products and 8 pathways, and the quartet PES displays 2 isomers, 2 transitionstates, 1 product and 4 pathways. After analysing the two kinds of PESs, twocompetitive pathways can be found on the doublet PES as follows: Path RP1(1): R(C2H+O2)→1→TS1-2→2 →TS2-6→6→TS6-P1 →P1(HCO+CO) Path RP2(4): R→1→TS1-P2→Complex1→P2 (HCCO+O) In pathway RP1(1), the relative energy of transition state TS1-2 is -212.22kJ.mol-1, however, in pathway RP2(4), the relative energy of transition stateTS1-Complex1 is -216.73 kJ.mol-1, and pathway RP2(4) has compared with thoseof pathway RP1(1). Therefore, we think that pathway RP2(4) is morepreferable to RP1(1), i.e., product P2 is the main product, and product P1 isminor. In addition, it is also possible that a little of products P3 and P5 areobtained. 2. The singlet and triplet potential energy surfaces (PES) of reaction HO2+ NO2 were systematically studied at the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p) level of the theory. The singlet PES showing 6 products,5 isomers, 16 transition states and 10 pathways is preferable to the triplet onefor this reaction. After analysing the pathways of the reaction, two competitivepathways on the singlet PES can be summarized as follows: Path RP1 (1):R(HO2+NO2)→TSR-P1 (OOHNO2)→P1(HNO2+O2) Path RP2 (4):R →TS1R-1 →1 →TS1-P2→P2 (trans-HONO+O2) Considering the conversion barrier heights and the relative energies of thetransition states involved in the two pathways, we think that Path RP2 (4) isthe major pathway of the reaction and Path RP1 (1) is minor pathway. ProductP2 (HCNO+O2) is the main product, and product P1 (HNO2+O2) is minor. Inaddition, it is also possible that a little of product P6 (NO3+OH) is obtained. 3. The doublet and quartet potential energy surfaces (PES) of reactionHO2+C2H2 were investigated at theCCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)level. The doublet PES exhibiting 10 products, 16 isomers, 26 transition statesand 10 pathways is preferable to the quartet one for the reaction. Fourcompetitive pathways on the doublet PES can be summarized as follows:Path RP1 (1):R(HO2+ C2H2)→1→2→3→4→5→P1(CH2O+HCO) Path RP2 (2):R→1→2→3→4→5→6→7→P2(CO2+CH3) Path RP3 (3):R→1→2→3→4→5→6→P3(CO+CH3O) Path RP7 (6):R→1→2→P7(C2H3O+O) Path RP1(1) is the major pathway and Path RP2(2) is the minor one.Path RP2(2) is preferable to Path RP3(3), and Path RP3(3) is preferable toPath RP7(6). 4. The singlet and triplet potential energy surfaces (PES) of reactionHO2+C2H were calculated at the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)level of the theory. The singlet PES represents 5 products, 9 isomers, 14transition states and 8 pathways. The triplet PES represents 2 products, 5isomers, 7 transition states and 2 pathways. After analyzing the two kinds ofPESs, two competitive pathways can be summarized as follows: Path RP1 (1):R(HO2+C2H)→1→3→4→P1(CO+H2CO) (singlet) Path RP7 :R(HO2+C2H)→3TSR-1→31→3TS1-P7→P7(HCCO+OH) (triplet) Path RP7 on the triplet PES is the major pathway of the reaction andPath RP1 (1) on the singlet PES is minor pathway. P7 (HCCO+OH) is themain product and P1 (CO+H2CO) is the minor. 5. The singlet and triplet potential energy surfaces (PES) of CS+O2reaction were calculated at the CCSD(T)/6-311G(d,p)//B3LYP/6-311G(d,p)level of the theory. The singlet PES shows 2 products, 3 isomers and 4transition states, and the triplet PES exhibits 1 product, 1 isomer and 2transition states. After analyzing the two kinds of PESs, two competitivepathways can be summarized as follows: Path RP1 (1):R(CS + O2)→TSR-1→1→TS1-2→2→TS2-3→3→TS3-P1 →P1(CO+SO) (singlet) Path RP3(6):R(CS + O2)→3TSR-1→31→3TS1-P3→P3(OCS+O) (triplet) Pathway RP3(6) on the triplet PES is the major pathway of the reaction更多还原