`ck2yaml` in v3 can't convert the same files as v2

[JacksonBurns]

Problem description

ck2yaml in Cantera 2.6.0 is able to convert my chemkin files, but 3.1.0 cannot

Steps to reproduce

The chem-gas.inp and chem-surface.inp files are attached to this issue:

demo.zip

and are also here: https://github.com/ReactionMechanismGenerator/RMG-Py/tree/a041fdeca81bf1ac6c56c3889a1c448707f55514/test/rmgpy/test_data/chemkin/chemkin_py/surface

I made two conda environments with cantera 2.6.0 (conda create --name cantera2 "python==3.9.*" "conda-forge::cantera<3") and 3.1.0 (conda create --name cantera3 "python==3.9.*" "conda-forge::cantera>2") and then run the following commands:

• conda run --name cantera2 ck2yaml --input chem-gas.inp --surface chem-surface.inp
• conda run --name cantera3 ck2yaml --input chem-gas.inp --surface chem-surface.inp

Behavior

v2 works:

$ conda run --name cantera2 ck2yaml --input chem-gas.inp --surface chem-surface.inp 
Wrote YAML mechanism file to 'chem-gas.yaml'.
Mechanism contains 6 species and 4 reactions.
Validating mechanism...
PASSED

but v3 says this:

conda run --name cantera3 ck2yaml --input chem-gas.inp --surface chem-surface.inp 
*******************************************************************************
Error while reading SITE section in chem-surface.inp starting on line 9:
"""
SITE   SDEN/2.4830E-09/ ! mol/cm^2
"""
SITE section defined with no site density
*******************************************************************************
Unable to convert mechanism due to errors. Please check
https://cantera.org/stable/userguide/ck2yaml-tutorial.html#debugging-common-errors-in-ck-files
for the correct Chemkin syntax.

ERROR conda.cli.main_run:execute(125): `conda run ck2yaml --input chem-gas.inp --surface chem-surface.inp` failed. (See above for error)

System information

• Cantera version: 2.6.0 and 3.1.0
• OS: Ubuntu 22.04
• Python/MATLAB/other software versions: python 3.9.21 in both cases

Attachments

Included in line above.

Additional context

I'm a developer of RMG and this came up when attempting to upgrade from Cantera 2 to 3 in this PR: ReactionMechanismGenerator/RMG-Py#2751

[JacksonBurns]

cc @sevyharris who was helping me with this as well and may be interested in this

[JacksonBurns]

Apologies for spam but I forgot to mention -

If I change the offending line from:

SITE   SDEN/2.4830E-09/ ! mol/cm^2
    X
    HX
	OX
	CH4X
    CH2OX2/2/
    CHOX3/3/
END

to

SITE/site0/   SDEN/2.4830E-09/ ! mol/cm^2
    X
    HX
	OX
	CH4X
    CH2OX2/2/
    CHOX3/3/
END

Then both versions work.

[speth]

Thanks for reporting this issue, @JacksonBurns. It appears to be a regression introduced in PR #1736.

[JacksonBurns]

Thanks for the quick fix :)