# Add new reactions using chemmech

**URL:** <https://forum.cmascenter.org/t/add-new-reactions-using-chemmech/2956>\
**Category:** CMAQ\
**Created:** [January 17, 2022, 3:30pm UTC](https://forum.cmascenter.org/t/add-new-reactions-using-chemmech/2956 "2022-01-17T15:30:18Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lwu127](https://avatars.discourse-cdn.com/v4/letter/l/ea666f/32.png) [@lwu127](https://forum.cmascenter.org/u/lwu127)\
**Post date:** [January 17, 2022, 3:30pm UTC](https://forum.cmascenter.org/t/add-new-reactions-using-chemmech/2956/1 "2022-01-17T15:30:18Z")

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Hi everyone,

I am using chemmech to add new reactions to the existing mechanism. One of the reactions i want to add is:

 ![2022-01-17 (2)](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/a/a1c9ffadafe02b21c1d9f33aed6191db550cae52.png)  
The reaction rate constant is given as k0 and kinf. However, i went over the guide for writing reaction rate constant. There is no such rate constant format (the types of reaction rate constant are given in the below picture).  
 ![2022-01-17 (4)](https://canada1.discourse-cdn.com/flex027/uploads/cmas/original/2X/e/ed0f54d494cb9fd18d90adc3bed5301b8df831a3.png)  
Can anyone help with formating this rate constant!  
Thanks!  
Lin

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**Author:** ![bhutzell](https://avatars.discourse-cdn.com/v4/letter/b/dfb087/32.png) [@bhutzell](https://forum.cmascenter.org/u/bhutzell)\
**Post date:** [January 21, 2022, 8:06pm UTC](https://forum.cmascenter.org/t/add-new-reactions-using-chemmech/2956/2 "2022-01-21T20:06:34Z")

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The nature of problem is unclear. Please reply with the formula that you wish to use to calculate the rate constant.