Update atom enthalpies for H, C, N, O, F, Cl, Br, I with data from ATcT #416
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cgrambow
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cgrambow
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| 'Li': 1.1, 'Be': 0.46, 'B': 0.29, 'C': 0.25, 'N': 1.04, 'O': 1.04, 'F': 1.05, 'Ne': 1.481, | ||
| 'Na': 1.54, 'Mg': 1.19, 'Al': 1.08, 'Si': 0.76, 'P': 1.28, 'S': 1.05, 'Cl': 1.1, | ||
| 'K': 1.481, 'Ca': 1.481, 'Ti': 1.802, 'Cu': 1.481, 'Zn': 1.481, 'Ge': 1.768, 'Br': 1.481, | ||
| atom_thermal = {'H': 1.012, 'He': 1.481, |
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There is a problem with how H( 0 k) and H(298K) presented, each uses their own standard state. So it Looks like I have to email ATCT and request thermal correction relative to H(298 K)
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Aren't atom_thermal just ideal gas corrections? They shouldn't change, right?
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I think they depend on Cp (int Cp=0 to Cp 298)
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Yes, they're the enthalpy increment of the elements (or 1/2 for diatomic reference states). Translational and rotational contributions are constant. If the vibrational frequencies of diatomics have changed in recent times, then the vibrational contribution could have changed, and if the excited state energy levels have changed in recent times, then the electronic contribution could have changed. My assumption would be that the frequencies and energy levels of diatomics are very well known, so these numbers should be accurate. I'll try to find recent frequencies and energy levels to calculate some of these numbers and see if my calculations agree.
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We do 2 for loops in [RMG-Py/arkane/encorr/corr.py](https://github.com/ReactionMechanismGenerator/RMG-Py/blob/74cee80a8c688b04dba265b2bb0b2a10724bee41/arkane/encorr/corr.py#L140) line 120 to 140. I Don't see a problem replacing with one for loop and use the J as units.
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Yes, it'll be exactly the same combining them into one number. What I'm trying to say is that it's better having them separate in the database because it makes for easier comparison with literature. For example, ATcT only lists atom_hf so a direct comparison to ATcT wouldn't be easy if we combine the numbers in the database.
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I agree with your comment that it would be easy to compare but the way we use/code we would never able to use that data. So why not combine?
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The way that Arkane separates all the terms (and then adds them back together) is the standard way to compute thermochemistry in literature, so I think we should keep it the way it is.
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By the way, I calculated the thermal corrections for all the gas phase diatomics, and my calculations agree with the values in the database.
cgrambow
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rwest
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I'm going to get this PR going. I used updated data from ATcT. Some things I noticed:
@dranasinghe, I assigned you to this PR. None of the existing BACs have been corrected yet based on the updated data.
Let's discuss.
RMG-Py PR: ReactionMechanismGenerator/RMG-Py#1955