Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

ATG for Intra RH Add Endocyclic family #578

Open
wants to merge 3 commits into
base: main
Choose a base branch
from

Conversation

kspieks
Copy link
Contributor

@kspieks kspieks commented Apr 26, 2022

This PR brings a few advancements to the Intra_RH_Add_Endocyclic reaction family. The discussion is motivated by this reaction C=CCC[CH]C=C>>[CH2]C1CCCC=C1 that had matched this template

  1. It runs ATG to standardize the rate tree. The results of running running ATG are stored in the zip file below. Previously, this family had about 80 groups defined. However, this family currently has no training reactions, so the resulting rate tree is very simple and only needs one node (which uses a previously defined heuristic approximation of the rate). I'm not sure why so many specific groups were previously defined when they all used the same rate rule.
  2. It defines a a forbidden group to prevent R3 in the template from being connected to a radical. After discussion with Xiaorui and Matt, we notice that R3=R2 really belongs to a [CH2]-C=C group for this reaction, and we don’t expect that reaction to proceed the same as when R2=R3 is actually an isolated double bond. Empirically, for this reaction, we were only able to find a TS for the ring opening/closing reaction or H transfer reaction, but not a TS for this family that involves both a ring formation and an H transfer, so we think this reaction is not elementary.

Currently, this family has no training reactions. Instead, a previously defined heuristic rule is used to estimate the rate for all reactions that match this family. The A-factor was arbitrarily set as 1e10 and the barrier was arbitrarily set to 5 kcal/mol. In my opinion, this rule at the root node is a gross overestimate as shown by the data below.

For this reaction, k(T=673K) = 4.757e8 1/s as seen on the RMG website

However, this reactant can also participate in an Intra_R_Add_Exocyclic reaction which has k(T=673K) = 8.48e4 1/s. The TST calculation was done in PR #570. This reaction actually has the radical attacking the double bound and since radicals are quite reactive, I would anticipate this reaction to be faster than the Intra_RH_Add_Endocyclic family. In an attempt to slow down the reaction rate of this family, I propose changing the Ea from 5 kcal/mol to 20 kcal/mol which would make k(T=673K) = 6.40e3 1/s. 20 kcal/mol is also an arbitrary choice so I'm open to suggestions. For what it's worth, changing the rate here probably has only minimal impact to our users since this family is not listed as one of the default families that people would likely be using.

Intra_RH_Add_Endo_rxn1.zip

@kspieks kspieks self-assigned this Apr 26, 2022
@kspieks kspieks force-pushed the Intra_RH_Add_Endo_forbidden_group branch from 3416daa to 8334c37 Compare May 25, 2022 20:08
@kspieks kspieks force-pushed the Intra_RH_Add_Endo_forbidden_group branch from 8334c37 to bc7c377 Compare May 25, 2022 21:14
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
Projects
None yet
Development

Successfully merging this pull request may close these issues.

1 participant