The constants A and B are given by(12)A=(0.0771-ν)5/6(13)B=A16(1-ν)k3πω2α3ln(γ0γ)where ν is the Poisson's ratio, ω is the angular rotation (in rad) between the initial and activated positions, α is the mean molecular radius, k is the Boltzmann constant, γ˙ is the net shear strain rate, and γ˙0 is the pre-exponential factor.