How can one calculate reaction rate constant?

["Alexei Khalizov" <khalizov-0at0-chemistry.mcgill.ca>]

 Dear CCLers,
 
 I would like to calculate rate constant k for bimolecular reaction A + B -> AB.
 I have found transition state and proved that it really connects reagents and
 products (G98w, GAMESS). According to RRKM the simplest expression for
 calculation of rate constant k is
 
 k = (kB*T/h)(Q??/Qa*Qb) exp(-Eo/RT),
 
 where kB is Boltzmann?s constant; Q??, Qa and Qb are partition functions for TS
 and reagents A and B; Eo ? difference in zero point energies of TS and
 reagents.
 
 Question: what units and what measure does this rate constant k have? Simple
 evaluation gives units of [s-1], but being a bimolecular it is expected to have
 units of  [M-1s-1], [cm3 molecules-1 s-1] or such. How can we account for
 this?
 
 Sincerely,
 Alexei Khalizov,
 Balakrishnan Viswanathan
 
 
 
 ------------------------- Dr. Alexei Khalizov Departments of Chemistry McGill
 University, 801 Sherbrooke St. W., Montreal, Quebec, CANADA, H3A 2K6