Learning Forum

[Biborka Boga]

Hi!
I am trying to perform the pre-processing of a LH mechanism file in Chemkin.

First, when I am performing the preprocessing in Chemkin for the reaction without considering the LH parameters, everything is fine.
As soon as I am specifying the LH parameters, the following error appears:

 1. A+B=>C+D+E+F       3.15E-03    0.0        0.0
      Error...3rd-body requires (+M) in reaction...LANG/A 1 0.0 0.0 0.95/
!! ERROR IN DATA STATEMENT NUMBER  1
SYNTAX ERROR, OR ILLEGAL VALUE
      Error...unrecognized 3rd-body species...LANG
      Error...problem finding 3rd-body parameter...LANG/A 1 0.0 0.0 0.95/
!! ERROR IN DATA STATEMENT NUMBER  1
SYNTAX ERROR, OR ILLEGAL VALUE
      Error...unrecognized 3rd-body species...LANG
      Error...problem finding 3rd-body parameter...LANG/O2 1 0.0 0.0 0.05/
      Error...unrecognized 3rd-body species...LHDE

P.S. For simplicity I have replaced the reactants and products with A, B, C...

Can you please offer me some hints how can I overcome these errors? I do not really have any idea about the menaing of 3rd body specie.
Thank you very much in advance!

[Judy Cooper]

Hi Biborka:

A lot of the errors are correct for the defiiencies in the mechanism.  The LH format has specific requirements.  For instance, for a reaction with 3rd bodies, the reaction must be of the form:

A+B+M=>AB 

where M is a wildcard that represents the 3rd body.  

M is an unspecified collision partner that carries away excess energy to stabilize the $\mathrm{A}\mathrm{B}$ molecule (forward direction) or supplies energy to break the $\mathrm{A}\mathrm{B}$ bond (reverse direction). 

The format required by LH is documented in the Chemkin Help Documentation -Chemkin Input Manual, which has a section for Gas Phase Chemistry.

I hope this helps.

 

[Biborka Boga]

Thank you very much your feedback! I will try again to import the mechanism considering your suggestions.