Reaction Orders and Surface Coverage Dependence

[Colton Shepard]

Hello, 

I am working with a particular surface chemistry reaction with a rate coefficient that takes the form 

k = A*T^b*exp(-Ea/(R*T))/B, 

where A is the pre-exponential factor, b is the exponent of temperature, Ea is the activation energy, and B is the surface site density in kmol/m^2. The rate of progress of this reaction is 

q = k*[G(s)], 

where [G(s)] is the concentration of the surface species in kmol/m^2. Since I do not know of a way to incorporate B into the pre-exponential factor, I rework the rate coefficient so that it is coverage dependent and change the order of the reaction so that it is not dependent on the concentration of G(s):

q = k*[G(s)] = A*T^b*exp(-Ea/(R*T))*([G(s)]/B) = k_modified*[G(s)]^0 = k_modified,

where I use the interface-Arrhenius reaction type with the parameters A=A, b=b, Ea=Ea in the rate-constant field and a=0, m=1, E=0 in the coverage-dependency field for G(s). When I implement this into Cantera, however, it seems that setting the order of G(s) to 0 somehow overrides the coverage dependency of k_modified so that it is the same as k, which should not be true. I have attached a bare working example of the reaction

O(s)->O+(s)

with the rate coefficient 

k = 1*T*exp(-1/(R*T))/B 

as a demonstration. Am I missing something? Can I not use reaction orders and coverage dependencies in the way I would like?

Thanks,

Colton