Active parameters are selected from uncertainty impact ranking as follows.

 

Number

Reaction

Uncertainty Factor f

1

H+O2<=>O+OH

1.15

2

O+H2<=>H+OH (low T)

1.6

3

O+H2<=>H+OH (high T)

1.6

4

OH+H2<=>H+H2O

1.2

5

2OH<=>O+H2O

1.4

6

H2+M<=>2H+M(N2)

3

6

H2+M<=>2H+M(H2)

3

6

H2+M<=>2H+M(H2O)

3

6

H2+M<=>2H+M(CO)

3

6

H2+M<=>2H+M(CO2)

3

7

H2+AR<=>2H+AR

2

12

O+H+M<=>OH+M(N2)

5

12

O+H+M<=>OH+M(H2O)

5

12

O+H+M<=>OH+M(CO)

5

12

O+H+M<=>OH+M(CO2)

5

13

H2O+M<=>H+OH+M(AR)

3.2

13

H2O+M<=>H+OH+M(HE)

3.2

13

H2O+M<=>H+OH+M(N2)

3.2

13

H2O+M<=>H+OH+M(H2)

3.2

13

H2O+M<=>H+OH+M(CO)

3.2

13

H2O+M<=>H+OH+M(CO2)

3.2

14

2H2O<=>H+OH+H2O

3.2

15

H+O2(+M)<=>HO2(+M) (k∞)

2

15

H+O2(+M)<=>HO2(+M)(AR)

2

15

H+O2(+M)<=>HO2(+M)(HE)

2

15

H+O2(+M)<=>HO2(+M)(N2)

2

15

H+O2(+M)<=>HO2(+M)(H2)

2

15

H+O2(+M)<=>HO2(+M)(O2)

2

15

H+O2(+M)<=>HO2(+M)(H2O)

2

15

H+O2(+M)<=>HO2(+M)(CO)

2

15

H+O2(+M)<=>HO2(+M)(CO2)

2

16

HO2+H<=>H2+O2

2

17

HO2+H<=>2OH

2

18

HO2+H<=>O+H2O

3

19

HO2+O<=>OH+O2

3

20

HO2+OH<=>H2O+O2

1.6

21

HO2+OH<=>H2O+O2

1.35

22

2HO2<=>H2O2+O2

1.5

23

2HO2<=>H2O2+O2

2

24

H2O2(+M)<=>2OH(+M) (k∞)

2.5

24

H2O2(+M)<=>2OH(+M)(AR)

2.5

24

H2O2(+M)<=>2OH(+M)(N2)

2.5

24

H2O2(+M)<=>2OH(+M)(H2)

2.5

24

H2O2(+M)<=>2OH(+M)(H2O)

2.5

24

H2O2(+M)<=>2OH(+M)(H2O2)

2.5

24

H2O2(+M)<=>2OH(+M)(CH2O)

2.5

25

H2O2+H<=>OH+H2O

2

26

H2O2+H<=>HO2+H2

2

27

H2O2+O<=>OH+HO2

3

28

H2O2+OH<=>H2O+HO2

2

29

H2O2+OH<=>H2O+HO2

1.3

30

CO+O(+M)<=>CO2(+M) (k∞)

10

31

CO+O2<=>O+CO2

10

32

CO+OH<=>H+CO2 (high T)

1.2

33

CO+OH<=>H+CO2 (low T)

1.5

35

HCO+M<=>H+CO+M(AR)

1.7

35

HCO+M<=>H+CO+M(HE)

1.7

35

HCO+M<=>H+CO+M(N2)

1.7

35

HCO+M<=>H+CO+M(H2)

1.7

35

HCO+M<=>H+CO+M(O2)

1.7

35

HCO+M<=>H+CO+M(H2O)

1.7

35

HCO+M<=>H+CO+M(CO)

1.7

35

HCO+M<=>H+CO+M(CH4)

1.7

35

HCO+M<=>H+CO+M(CH2O)

1.7

36

HCO+H<=>H2+CO

2.5

38

HCO+O<=>H+CO2

2

39

HCO+OH<=>H2O+CO

2

40

HCO+O2<=>HO2+CO

2

43

CH+H<=>C+H2

1.5

46

CH+H2<=>H+CH2

3

47

CH+H2(+M)<=>CH3(+M)(AR)

2

50

CH+O2<=>CO2+H

1.6

51

CH+O2<=>CO+OH

1.6

52

CH+O2=>O+H+CO

1.6

57

CH2+OH<=>H+CH2O

3

60

CH2+H2<=>H+CH3

9

61

CH2+O2=>OH+H+CO

2

62

CH2+O2=>2H+CO2

2

63

CH2+O2<=>O+CH2O

2

64

CH2+O2<=>H2+CO2

2

76

CH2(S)+H2<=>CH3+H

2

85

HCO+H(+M)<=>CH2O(+M) (k∞)

3

85

HCO+H(+M)<=>CH2O(+M)(AR)

3

85

HCO+H(+M)<=>CH2O(+M)(CH2O)

3

86

CH2O(+M)<=>H2+CO(+M)(AR)

2.5

87

CH2O+H<=>HCO+H2

2

88

CH2O+O<=>OH+HCO

1.6

89

CH2O+OH<=>HCO+H2O

2

90

CH2O+O2<=>HO2+HCO

3

91

CH2O+HO2<=>HCO+H2O2

3

97

CH3+H(+M)<=>CH4(+M) (k∞)

2

97

CH3+H(+M)<=>CH4(+M)(AR)

3

97

CH3+H(+M)<=>CH4(+M)(HE)

3

97

CH3+H(+M)<=>CH4(+M)(N2)

3

97

CH3+H(+M)<=>CH4(+M)(O2)

3

97

CH3+H(+M)<=>CH4(+M)(H2O)

3

97

CH3+H(+M)<=>CH4(+M)(CO)

3

98

CH3+O<=>H+CH2O

1.4

99

CH3+O=>H+H2+CO

1.4

101

CH3+OH<=>CH2+H2O

2

102

CH3+OH<=>CH2(S)+H2O

3

103

CH3+OH<=>H2+CH2O

3

104

CH3+HO2<=>O2+CH4

3

105

CH3+HO2<=>OH+CH3O

3

106

CH3+O2<=>O+CH3O

2

107

CH3+O2<=>OH+CH2O

3

109

CH3+CH<=>H+C2H3

10

110

CH3+CH2<=>H+C2H4

3

112

2CH3(+M)<=>C2H6(+M) (k∞)

2

112

2CH3(+M)<=>C2H6(+M)(AR)

2

112

2CH3(+M)<=>C2H6(+M)(O2)

2

112

2CH3(+M)<=>C2H6(+M)(CH4)

2

113

2CH3<=>H+C2H5

2

115

CH3+CH2O<=>HCO+CH4

2

127

CH2OH(+M)<=>H+CH2O(+M)(AR)

2

127

CH2OH(+M)<=>H+CH2O(+M)(H2O)

2

130

CH2OH+H<=>OH+CH3

2.5

134

CH2OH+O2<=>HO2+CH2O

2

136

CH4+H<=>CH3+H2

1.5

137

CH4+O<=>OH+CH3

1.4

138

CH4+OH<=>CH3+H2O

1.2

139

CH4+HO2<=>CH3+H2O2

2.5

141

CH4+CH2<=>2CH3

2

142

CH4+CH2(S)<=>2CH3

1.4

172

HCCO+O2<=>OH+2CO

5

176

C2H2(+M)<=>H2CC(+M)(AR)

3

178

C2H2+O<=>H+HCCO

2

179

C2H2+O<=>CO+CH2

3.2

185

H2CC+O2<=>2HCO

5

188

CH2CO+H<=>CH3+CO

3

199

C2H3+H<=>H2CC+H2

4

204

C2H3+O2<=>HCO+CH2O

2

205

C2H3+O2<=>CH2CHO+O

3

237

C2H4(+M)<=>H2+H2CC(+M) (k∞)

2

237

C2H4(+M)<=>H2+H2CC(+M)(AR)

2

237

C2H4(+M)<=>H2+H2CC(+M)(CH4)

2

238

C2H4+H(+M)<=>C2H5(+M) (k∞)

2

238

C2H4+H(+M)<=>C2H5(+M)(N2)

2

238

C2H4+H(+M)<=>C2H5(+M)(H2O)

2

239

C2H4+H<=>C2H3+H2

2.5

240

C2H4+O<=>CH3+HCO

2

243

C2H4+OH<=>C2H3+H2O

2

249

C2H5+H(+M)<=>C2H6(+M)(AR)

2

254

C2H5+O2<=>HO2+C2H4

2

258

C2H6+H<=>C2H5+H2

1.4

259

C2H6+O<=>OH+C2H5

2

260

C2H6+OH<=>C2H5+H2O

1.6

261

C2H6+CH<=>CH3+C2H4

3

264

C2H6+CH3<=>C2H5+CH4

1.5

999

flw_1a [OH]0 (nominal: 100 ppm)

10

999

flw_2a [OH]0 (nominal: 100 ppm)

10

999

flw_3a [OH]0 (nominal: 10 ppm)

2

999

flw_4a [OH]0 (nominal: 40 ppm)

10

Special treatment is required for unimolecular reactions. In active parameter analysis, absolute low-pressure limit reaction rates with each collider was assumed to have the same uncertainty factor as the base rate coefficient (usually with N2 or Ar). In the optimization, however, third-body efficiencies relative to the base collider are considered as independent variables within a reasonable range. For the H+O2+M reaction, th ranges of relative third-body efficiencies are (expressed in the nomalized rate variable) He: ±0.3; Ar: ±0.2; O2: ±0.3; H2O: ±7; CO2: ±1.4; H2: ±1. For other, generic relative efficiencies, the ranges are: Ar, He: -0.2/+0.3; O2: ±0.2; CO: ±0.5; H2O ±3; CH4, CO2: ±1; H2: ±30%. Uncertainty factors of third body efficiencies are obtained by averaging the upper and lower bounds mentioned above.