In this dissertation, the reaction of C(3P) + GeH4 (1A1) is explored by combining the electronic structure and statistical calculations. The reaction was found to form an initial van der Waals complex in the original channel, with this path of triplet to singlet potential surfaces existing from the intersystem crossing (ISC). On both triplet and singlet surfaces, we use b3lyp to predict the correct path for a compound, and then use the method called CCSD/cc-pVTZ to optimize the reactant, intermediates, transition states and dissociation compounds. Going one step further, the energies generated are calculated by CCSD/CBS with CCSD/cc-pvtz zero-point energy correction. The statistical RRKM theory is employed in calculating the rate constant and the evolution of the concentration over time.

Theoretical study of C(3P) + GeH4 (1A1) reaction
1. Introduction………………………………………………………………………1
2. Theoretical methods……………………………………………………………...3
2.1 Hybrid functional b3lyp………………………………………...….……...3
2.2 Coupled cluster CCSD(T)…………………………………………………3
2.3 RRKM(Rice-Ramsperger-Kassel-Marcus theory)…………………....…4
2.3.1 RRKM theory………………………………………………………...4
3. Result and discussion…………………………………………………………….5
3.1 Reaction paths on triplet potential surface………………………………6
3.1.1 Reaction paths………………………………………………………..6
3.1.2 Products……………………………………………………………...11
H atom dissociation products…………………………………………..…11
H2-elimination products…………………………………………………...11
3.1.3 Evolution of concentration with time……………………………...12
0 kJ/mol collision energy…………………………………………...……..12
15 kJ/mol collision energy………………………………………...………13
35.5 kJ/mol collision energy…………………………………...…….……14
3.2 Reaction paths on singlet potential surface…………………………..…15
3.2.1 Reaction paths………………………………………………………15
3.2.2 Products………………………………………………………...……20
H atom dissociation products…………………………………………..…21
H2-elimination products…………………………………….……………..21
3.2.3 Evolution of concentration with time…………………………..….21
0 kJ/mol collision energy………………………………………….....……21
15 kJ/mol collision energy………………………………………...…...….23
35.5 kJ/mol collision energy………………………………………..……..24
3.3 Branching ratio…………………………………………………………...25
3.4 Comparison with an experiment..…………………………………….....28
4. Conclusion……………………………………………………………………...29
Reference…………………………………………………………………......……...31

Table 1. C(3P) + GeH4 (1A1) energies with cc-pvtz basis set………………………33
Table 2. The RRKM rate constant(s-1) of singlet.……………………………........37
Table 3. The RRKM rate constant(s-1) of triplet………………………………….39
Table 4. Calculation of branching ratio of CGeH4 products of singlet………….40
Table 5. Calculation of branching ratio of CGeH4 products of triplet…………..40
Table 6. Branching ratio of CGeH4 products of singlet via different channel…..40
Table 7. Branching ratio of CGeH4 products of triplet via different channel…..41
Figure 1. The whole probable pathways of C(3P) + GeH4 (1A1)………………….42
Figure 2. Singlet pathways of C(3P) + GeH4 (1A1)…………………………………43
Figure 3. Triplet pathways of C(3P) + GeH4 (1A1)…………………………………44
Figure 4. The CCSD/cc-pvtz optimized geometries of reactant……………….....45
Figure 5. The CCSD/cc-pvtz optimized geometries of intermediates…………....46
Figure 6. The CCSD/cc-pvtz optimized geometries of products…………………47
Figure 7. The CCSD/cc-pvtz optimized geometries of transition state…….…….49
Figure 8. The reaction mechanism of singlet…………………………………..….53
Figure 9. The reaction mechanism of triplet……………………………………....55
Figure 10 a. The singlet state concentration evolution with time – 0 kJ..………56
Figure 10 b. The singlet state concentration evolution with time – 15 kJ…....…58
Figure 10 c. The singlet state concentration evolution with time -35.5 kJ………60
Figure 11 a. The triplet state concentration evolution with time – 0 kJ..…...…..62
Figure 11 b. The triplet state concentration evolution with time – 15 kJ…..…...64
Figure 11 c. The triplet state concentration evolution with time -35.5 kJ…..…..66
Figure 12. The IRC paths of each channel….…………………………………..…68

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