ReactionMechanismGenerator / ReactionMechanismGenerator/RMG-database

NO gas missing R*ln(2) in entropy in PrimaryThermoLibrary

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Python
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Description

It appears that the species "NOJ" in PrimaryThermoLibrary.py is estimating entropy incorrectly. This was discovered when looking at the rate of NO oxidation to NO2 on Pt(111). We saw that oxidation was occurring beyond equilibrium at high temperature. This we discovered was due to an underestimation of entropy by about 1.4 cal/mol which is approximately R*ln(2), or the entropy from electronic degeneracy of NO. While PrimaryThermoLibrary.py gets it wrong, NOx2018.py gets it right, and stems from the ATcT.

This was discussed in the RMG-Cat development meeting today, and the recommendations from this discussion were to fix the instances where NO is assigned an incorrect NASA7 polynomial. It is recognized that there may be other species that are wrong too, and we should perhaps search for the root cause of this error and other species impacted. The other suggestion is to create a new thermo library using the ATcT NASA7 polynomials that we have. Here is a file with those values from C. Franklin Goldsmith, and before that, from Branko Ruscic I believe:

ATcT_polynomials.yaml

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  3. Fork the repository and make your change on a branch.
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Research direction

Start with the NOJ entry and NASA7 polynomial in input/thermo/libraries/primaryThermoLibrary.py, then compare it with the corresponding entry in input/thermo/libraries/NOx2018.py and the supplied ATcT_polynomials.yaml. Review related NO assignments for the same discrepancy. Done means the incorrect instances are identified and corrected or the affected scope is documented, with the ATcT values preserved.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
data, databases
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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