Irreversible singlet reaction becomes reversible in PDEP

[sevyharris]

Bug Description

I recently generated a butane combustion mechanism that starts off by converting a bunch of triplet oxygen into the singlet form.

The O2(s) <=> O2 reaction is a Chebyshev PDEP, using kinetics from the Singlet_Val6_to_triplet family for the high pressure limit.

The rate in the database is NOT reversible and is only supposed to be for the singlet -> triplet direction, but the reaction made by the PDEP network IS reversible, and then leads to the formation of singlet oxygen.

An important detail is that the mechanism already has singlet oxygen in the core when it goes to make this reaction. As to how the singlet O2 got there, that's a separate issue I'll post next.

How To Reproduce

Input file
Chemkin file
RMG log
Species dictionary

Expected Behavior

If the Singlet_Val6_to_triplet rule is irreversible, I would expect any reactions derived from it to also be irreversible. The mechanism should not be generating singlet oxygen from triplet oxygen.

Installation Information

Describe your installation method and system information.

• OS: ubuntu
• Installation method: source
• RMG version information:
  • RMG-Py: I'm on my https://github.com/sevyharris/RMG-Py/tree/autoscience_uncertainties_2025 6cf97c3
  • RMG-database: https://github.com/sevyharris/RMG-database/tree/my_bac 9ccc3952e0acef53cbbc7cd3be7558101da1a016

Additional Context

will post the pdep file shortly