cathodic transfer coefficient, α c

For a reaction with a single rate-determining step
α c ν = − R T n F ( ∂ ( ln ( | I c | ) ) ∂ E ) T , p , c i , ...
where α c is the cathodic transfer coefficient (number), R is the gas constant, T is the thermodynamic temperature, and ν the stoichiometric number giving the number of identical activated complexes formed and destroyed in the completion of the overall reaction as formulated with the transfer of n electrons.
PAC, 1974, 37, 499 (Electrochemical nomenclature) on page 515