Subject: NO2+NO3+M ---> N2O5+M

From: <[email-masked]>
Date: Mon, 31 Jul 95 22:41:06+0530

Dear Netters:
We are interested in the rate constant value for the reaction
          NO2 + NO3 + M ------> N2O5 + M       .....(1)
and  similar reactions as well, using semi-empirical  method.  To 
start with,  we  have  constructed a super  molecule  between NO2 
and NO3 wherein the interatomic distance between the two separate 
moieties was kept very large.
          NO2 ...... NO3
The potential energy surface (PES) was then traced as a  function 
of  the inter atomic distance. From the PES the transition  state 
structure  was  obtained.  Then,  we  have  calculated  the  rate 
constant using the Arrhenius rate equation. The frequency  factor 
"A" was assumed to be 10^11 cc mole^-1 sec^-1 (assuming as if a
bimolecular reaction).
Our question is the following:
i)  since the reaction (1) is a termolecular reaction, should  we 
have to use some other frequency factor,
ii) since the semiempirical method does not consider "M",  should 
we have to add some compensatory factor,
iii) can  we compare the rate constant of the reaction  (1)  with 
other bimolecular reactions which do not involve "M".

Thanks  in  advance  for your comments and  suggestions.  I  will 
summarize after receiving from you. Thank you once again.

S. Parthiban
Department of Aerospace Engineering, 
Indian Institute of Science
Bangalore-560012, INDIA   
E-Mail: [email-masked]