O=C=C=C=O thermo

[davidfarinajr]

Thermo group additivity estimation for O=C=C=C=O (https://rmg.mit.edu/database/thermo/molecule/1%20O%20u0%20p2%20c0%20%7B2,D%7D%0A2%20C%20u0%20p0%20c0%20%7B1,D%7D%20%7B3,D%7D%0A3%20C%20u0%20p0%20c0%20%7B2,D%7D%20%7B4,D%7D%0A4%20C%20u0%20p0%20c0%20%7B3,D%7D%20%7B5,D%7D%0A5%20O%20u0%20p2%20c0%20%7B4,D%7D%0A)

is significantly off from ATcT (https://atct.anl.gov/Thermochemical%20Data/version%201.122p/species/?species_number=279).

H298 from GAV is +34 kcal/mol and ATcT H298 is -22 kcal/mol.

We can add O=C=C=C=O to a thermo library (perhaps primaryThermoLibrary), but we should look into thermo groups more closely to see if this error is systematic for these types of molecules

[davidfarinajr]

smiles	h298_gav_master	s298_gav_master	h298_gav_pr	s298_gav_pr	h298_G4	s298_G4
O=C=C=C=O	34.2	4.62	34.2	4.62	-22.38	65.8
O=C=C=C=C=O	68.4	10.62	35.26	75.1	50.42	73.41
O=C=C=C=C=C=O	102.6	16.62	69.46	81	43.5	70.3

units are kcal/mol, cal/mol/k

[davidfarinajr]

PR is thermo groups using this PR branch https://github.com/ReactionMechanismGenerator/RMG-database/pull/473 which adds a Cdd-(Cdd-O2d)Cds group

[davidfarinajr]

Seems to be a systematic issue with O=C=C...C=O molecules. Both the master and PR branches are quite poor at O=C=C=C=O so that could be added to thermo library, but the PR branch looks like it's better for the other molecules, especially for entropy, than the master branch.

[rwest]

Is this issue fully addressed by #478 and #473 and other thermo group improvements? can it be closed?