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 nonrigid 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. 

 
Representative Geometry of [H2] (g)  
spin ON spin OFF  
Top contributors to the provenance of Δ_{f}H° of [H2] (g)The 2 contributors listed below account for 100.0% of the provenance of Δ_{f}H° of [H2] (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.  

Influence Coefficient  TN ID  Reaction  Measured Quantity  Reference 

0.942  74.1  [H2] (g) → H (g) + H (g)  Δ_{r}H°(0 K) = 8819.364 ± 100 cm1  Srivastava 2012, est unc 
0.057  72.6  [H2] (g) → H2 (g)  Δ_{r}H°(0 K) = 2.63 ± 0.05 eV  Srivastava 2012, est unc 
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, 99799997 (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 21^{st} Century. J. Phys. Conf. Ser. 16, 561570 (2005) [DOI: 10.1088/17426596/16/1/078] 

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 HighLevel Calculations and the Active Thermochemical Tables Approach. J. Phys. Chem. A 123, 34813496 (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 CoupledCluster Theory: The Methyl and Ethyl Peroxy Families. J. Phys. Chem. A 123, 56735682 (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, 42124231 (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, 10971101 (2014) [DOI: 10.1002/qua.24605] 