Reaction dynamics of ground-state atomic silicon (Si; 3P) with singlet1,3-butadiene(C4H6) under single-collision conditions are studied theoretically. Electronic structure calculations suggest the formation of singlet SiC4H4 isomers along with molecule hydrogen via singlet SiC4H6 collision complexes, which then proceed through intersystem crossing from triplet to singlet potential energy surface. All possible reaction products are either cyclic or linear structure. The complexes, intermediates, transition states, and elimination products are optimized at the level of B3LYP/cc-pVTZ. Furthermore, the energies are calculated by CCSD(T)/pVTZ, CCSD(T)/pVDZ, and CCSD(T)/pVQZ, which are extrapolated to complot basis set limit, CCSD(T)/CBS with zero-point energy corrections from B3YLP/cc-pVTZ level.
Last, the most probable pathways can be predicted by calculating RRKM rate constants.

Abstract
Contents………………………………………………………………………………I

Reaction dynamics of Si (3P) + 1,3-Butadiene (CH2CHCHCH2)
I. Introduction………………………………………………………………………1
II. Theoretical methods……………………………………………………………5
1. Ab initio electronic structure calculations………………………………5
2. RRKM rate constants calculations ……5
3. CBS(Complete Basis Set)………………………………………………6
4. Branching ratios calculations & Concentration evaluation with time…6
5. Reaction conical intersection……………………………………………7
6. Most probable path scheme………………………………………………7
III. Results and Discussion……………………………………………………………9
1. Single collision condition complex triplet & singlet c1……9
2. The reaction pathways……………………………………………9
3. The most probable pathways of 1c1……………………………………21
4. H2 molecule elimination products…………………………………………………22
5. Reaction mechanism of 1c1……………………………………………23
6. Concentration versus time………………………………………………23
7. IRC (Intrinsic Reaction Coordinate)……………………………………24
8. Tables and Figures………………………………………………………24
9. Comparison with experiment……………………………………………24
IV. Conclusions………………………………………………………………………27
V. References……………………………………………………………………29
Table 1. Si+1,3-butadiene energy with cc-pVTZ basis set………………33
Table 2. The RRKM rate constants………………………………………49
Table 3. Relative dissociate yields of the reactant………………………………57
Figure 1. The reaction pathway of 1c1……………………………………………58
Figure 2. The reaction pathway of 1c16……………………………………………59
Figure 3. The reaction pathway of 1i7'……………60
Figure 4. The reaction pathway of 1i31…………………………………………61
Figure 5. The reaction pathway of 1i7…………………………………………62
Figure 6. The reaction pathway of 1i6……………………………………………63
Figure 7. The reaction pathway of 1i19……………………………………………64
Figure 8. The reaction pathway of 1i39………………65
Figure 9. The reaction pathway of 1i41………………………………………66
Figure 10. The reaction pathway of 1i66……………………………………67
Figure 11. The reaction pathway of 1i1………………………………………68
Figure 12. The reaction pathway of 1i18……………………………………69
Figure 13. The most probable pathway of 1c1…………………………………70
Figure 14. The optimized geometries of the reactant and complexes…71
Figure 15. The optimized geometries of the intermediates……………………72
Figure 16. The optimized geometries of the variational transition state………86
Figure 17. The optimized geometries of the transition state……………87
Figure 18. The optimized geometries of the products…………………109
Figure 19. The reaction mechanism………………………………114
Figure 20. The concentration versus time……………………………………114
Figure 21. The IRC paths of each channel…………………………………119
Scheme 1&2. ………………………………………………………………………162

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