Selected ATcT [1, 2] enthalpy of formation based on version 1.122r of the Thermochemical Network [3]

This version of ATcT results was generated from an expansion of version 1.122q [4, 5] to include a non-rigid rotor anharmonic oscillator (NRRAO) partition function for hydroxymethyl [6], as well as data on 42 additional species, some of which are related to soot formation mechanisms.

Species Name Formula Image    ΔfH°(0 K)    ΔfH°(298.15 K) Uncertainty Units Relative
Molecular
Mass		 ATcT ID
DisiliconSi2 (g)[Si][Si]587.8591.7± 1.7kJ/mol56.17100 ±
0.00060		12597-35-2*0

Top contributors to the provenance of ΔfH° of Si2 (g)

The 9 contributors listed below account for 71.4% of the provenance of ΔfH° of Si2 (g).

Please note: The list is limited to 20 most important contributors or, if less, a number sufficient to account for 90% of the provenance. The Reference acts as a further link to the relevant references and notes for the measurement. The Measured Quantity is normaly given in the original units; in cases where we have reinterpreted the original measurement, the listed value may differ from that given by the authors. The quoted uncertainty is the a priori uncertainty used as input when constructing the initial Thermochemical Network, and corresponds either to the value proposed by the original authors or to our estimate; if an additional multiplier is given in parentheses immediately after the prior uncertainty, it corresponds to the factor by which the prior uncertainty needed to be multiplied during the ATcT analysis in order to make that particular measurement consistent with the prevailing knowledge contained in the Thermochemical Network.

Contribution
(%)		TN
ID		 Reaction Measured Quantity Reference
29.66343.8 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 74.96 ± 0.30 kcal/molFeller 2008
9.06391.1 Si (cr,l) + 2 F2 (g) → SiF4 (g) ΔrH°(298.15 K) = -385.98 ± 0.19 kcal/molWise 1963, Wise 1962
6.16430.1 SiH3SiH3 (g) → 2 Si (cr,l) + 3 H2 (g) ΔrH°(298.15 K) = -19.1 ± 0.6 (×1.445) kcal/molGunn 1961, est unc
5.86343.7 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 74.2 ± 0.4 (×1.682) kcal/molFeller 1999a
5.86340.2 Si (cr,l) → Si (g) ΔrG°(1525 K) = 231.1 ± 2.0 kJ/molBatdorf 1959, 3rd Law
4.66397.1 SiH4 (g) → Si (cr,l) + 2 H2 (g) ΔrH°(298.15 K) = -8.3 ± 0.5 kcal/molGunn 1961, Gurvich TPIS, est unc
4.06355.1 Si (cr,l) + O2 (g) → SiO2 (cr,l) ΔrH°(298.15 K) = -217.58 ± 0.35 kcal/molGood 1964, Good 1962, King 1951
3.46390.8 SiF4 (g) → Si (g) + 4 F (g) ΔrH°(0 K) = 565.92 ± 0.30 kcal/molKarton 2011
2.86371.6 SiO2 (cr,l) + Si (cr,l) → 2 SiO (g) ΔrG°(1618 K) = 37.94 ± 0.29 (×1.477) kcal/molRamstad 1961, 3rd Law, Gurvich TPIS

Top 10 species with enthalpies of formation correlated to the ΔfH° of Si2 (g)

Please note: The correlation coefficients are obtained by renormalizing the off-diagonal elements of the covariance matrix by the corresponding variances.
The correlation coefficient is a number from -1 to 1, with 1 representing perfectly correlated species, -1 representing perfectly anti-correlated species, and 0 representing perfectly uncorrelated species.

Correlation
Coefficent
(%)		Species Name Formula Image    ΔfH°(0 K)    ΔfH°(298.15 K) Uncertainty Units Relative
Molecular
Mass		 ATcT ID
91.1 Disilicon anion[Si2]- (g)[Si][Si-]375.5379.4± 1.9kJ/mol56.17155 ±
0.00060		64236-73-3*0
75.9 SiliconSi (g)[Si]450.53454.86± 0.64kJ/mol28.08550 ±
0.00030		7440-21-3*0
75.9 Silicon anionSi- (g)[Si-]316.46319.44± 0.64kJ/mol28.08605 ±
0.00030		14337-02-1*0
75.9 Silicon cationSi+ (g)[Si+]1237.041241.17± 0.64kJ/mol28.08495 ±
0.00030		14067-07-3*0
64.7 SilaneSiH4 (g)[SiH4]42.8833.27± 0.70kJ/mol32.11726 ±
0.00041		7803-62-5*0
64.7 DisilaneSiH3SiH3 (g)[SiH3][SiH3]92.376.3± 1.4kJ/mol62.21864 ±
0.00073		1590-87-0*0
60.3 Disilicon cation[Si2]+ (g)[Si][Si+]1350.21353.8± 2.8kJ/mol56.17045 ±
0.00060		12597-36-3*0
60.0 SilylidyneSiH (g)[SiH]371.45373.24± 0.81kJ/mol29.09344 ±
0.00031		13774-94-2*0
48.1 MethylsilaneCH3SiH3 (g)C[SiH3]-9.46-25.63± 0.96kJ/mol46.14384 ±
0.00095		992-94-9*0
45.8 OxosilyleneSiO (g)[Si]=O-98.11-96.95± 0.65kJ/mol44.08490 ±
0.00042		10097-28-6*0

Most Influential reactions involving Si2 (g)

Please note: The list, which is based on a hat (projection) matrix analysis, is limited to no more than 20 largest influences.

Influence
Coefficient		 TN
ID		 Reaction Measured Quantity Reference
0.7286343.8 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 74.96 ± 0.30 kcal/molFeller 2008
0.5906345.1 [Si2]- (g) → Si2 (g) ΔrH°(0 K) = 2.202 ± 0.010 eVArnold 1993, Kitsopoulos 1991
0.4266389.4 SiC (g) + [Si2]+ (g) → [SiC]+ (g) + Si2 (g) ΔrH°(0 K) = 1.033 ± 0.030 eVRuscic W1RO
0.4096345.2 [Si2]- (g) → Si2 (g) ΔrH°(0 K) = 2.199 ± 0.012 eVNimlos 1987
0.3196344.6 Si2 (g) → [Si2]+ (g) ΔrH°(0 K) = 7.905 ± 0.040 eVRuscic W1RO
0.1596389.2 SiC (g) + [Si2]+ (g) → [SiC]+ (g) + Si2 (g) ΔrH°(0 K) = 1.001 ± 0.049 eVRuscic G4
0.1446343.7 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 74.2 ± 0.4 (×1.682) kcal/molFeller 1999a
0.0996389.1 SiC (g) + [Si2]+ (g) → [SiC]+ (g) + Si2 (g) ΔrH°(0 K) = 1.015 ± 0.062 eVRuscic G3X
0.0956344.4 Si2 (g) → [Si2]+ (g) ΔrH°(0 K) = 7.924 ± 0.073 eVRuscic G4
0.0596344.3 Si2 (g) → [Si2]+ (g) ΔrH°(0 K) = 7.895 ± 0.093 eVRuscic G3X
0.0526344.5 Si2 (g) → [Si2]+ (g) ΔrH°(0 K) = 7.819 ± 0.099 eVRuscic CBS-n
0.0386389.5 SiC (g) + [Si2]+ (g) → [SiC]+ (g) + Si2 (g) ΔrH°(0 K) = 1.03 ± 0.10 eVBruna 1981, est unc
0.0296389.3 SiC (g) + [Si2]+ (g) → [SiC]+ (g) + Si2 (g) ΔrH°(0 K) = 1.140 ± 0.066 (×1.719) eVRuscic CBS-n
0.0296343.6 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 74.17 ± 1.50 kcal/molRuscic W1RO
0.0256343.4 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 75.15 ± 1.60 kcal/molRuscic G4
0.0246348.1 Si (cr,l) + Si (g) → Si2 (g) ΔrG°(1800 K) = 13.9 ± 1.9 kcal/molChatillon 1975, 3rd Law
0.0226344.1 Si2 (g) → [Si2]+ (g) ΔrH°(0 K) = 8.00 ± 0.15 eVWinstead 1995, Winstead 1995a, est unc
0.0226343.3 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 76.07 ± 1.72 kcal/molRuscic G3X
0.0206387.2 2 SiC (cr, alpha-hex) → Si2 (g) + 2 C (graphite) ΔrH°(2000 K) = 165 ± 5 (×1.044) kcal/molDrowart 1958, 3rd Law
0.0146343.5 Si2 (g) → 2 Si (g) ΔrH°(0 K) = 73.29 ± 2.16 kcal/molRuscic CBS-n
References
1   B. Ruscic, R. E. Pinzon, M. L. Morton, G. von Laszewski, S. Bittner, S. G. Nijsure, K. A. Amin, M. Minkoff, and A. F. Wagner,
Introduction to Active Thermochemical Tables: Several "Key" Enthalpies of Formation Revisited.
J. Phys. Chem. A 108, 9979-9997 (2004) [DOI: 10.1021/jp047912y]
2   B. Ruscic, R. E. Pinzon, G. von Laszewski, D. Kodeboyina, A. Burcat, D. Leahy, D. Montoya, and A. F. Wagner,
Active Thermochemical Tables: Thermochemistry for the 21st Century.
J. Phys. Conf. Ser. 16, 561-570 (2005) [DOI: 10.1088/1742-6596/16/1/078]
3   B. Ruscic and D. H. Bross,
Active Thermochemical Tables (ATcT) values based on ver. 1.122r of the Thermochemical Network, Argonne National Laboratory, Lemont, Illinois 2021 [DOI: 10.17038/CSE/1822363]; available at ATcT.anl.gov
4   D. Feller, D. H. Bross, and B. Ruscic,
Enthalpy of Formation of C2H2O4 (Oxalic Acid) from High-Level Calculations and the Active Thermochemical Tables Approach.
J. Phys. Chem. A 123, 3481-3496 (2019) [DOI: 10.1021/acs.jpca.8b12329]
5   B. K. Welch, R. Dawes, D. H. Bross, and B. Ruscic,
An Automated Thermochemistry Protocol Based on Explicitly Correlated Coupled-Cluster Theory: The Methyl and Ethyl Peroxy Families.
J. Phys. Chem. A 123, 5673-5682 (2019) [DOI: 10.1021/acs.jpca.8b12329]
6   D. H. Bross, H.-G. Yu, L. B. Harding, and B. Ruscic,
Active Thermochemical Tables: The Partition Function of Hydroxymethyl (CH2OH) Revisited.
J. Phys. Chem. A 123, 4212-4231 (2019) [DOI: 10.1021/acs.jpca.9b02295]
7   B. Ruscic,
Uncertainty Quantification in Thermochemistry, Benchmarking Electronic Structure Computations, and Active Thermochemical Tables.
Int. J. Quantum Chem. 114, 1097-1101 (2014) [DOI: 10.1002/qua.24605]
Formula The aggregate state is given in parentheses following the formula, such as: g - gas-phase, cr - crystal, l - liquid, etc.
Uncertainties The listed uncertainties correspond to estimated 95% confidence limits, as customary in thermochemistry (see, for example, Ruscic [7]).
Note that an uncertainty of ± 0.000 kJ/mol indicates that the estimated uncertainty is < ± 0.0005 kJ/mol.
Website Functionality Credits The reorganization of the website was developed and implemented by David H. Bross (ANL).
The find function is based on the complete Species Dictionary entries for the appropriate version of the ATcT TN.
The molecule images are rendered by Indigo-depict.
The XYZ renderings are based on Jmol: an open-source Java viewer for chemical structures in 3D. http://www.jmol.org/.
Acknowledgement This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences under Contract No. DE-AC02-06CH11357.