Activation function Heaviside

In this relation, E is the Arrhenius activation energy of an elementary chemical reaction the coefficient a is the efficiency of excitation energy in overcoming the aetiva-tion barrier kRo is the pre-exponential factor and 9 x — xo) is the Heaviside function... 

In this relation, x, j are translational energies of particles before and after elementary reaction (6-2) i a 3 eV/mol is the activation energy of reaction (6-2) 5( ), 9(e), r(n) are the Dirac 5-function, the Heaviside step function, and the gamma-function, respectively and tico and v are the vibrational qrrantrrm and vibrational quantum number of N2. The distribution frmction Fv( j, 7) of products of the reverse elementary process N -I- NO N2(w) + O over their translational energy can be presented as the prior-expectation distribution frmction of the theoretical-informational approach developed by Ben-Shaul, Levine, Bernstein (1974 Levine Bernstein, 1975) ... 

For quiescent crystallization under a constant temperature, in the case of instantaneous nucleation with a constant number density No, one obtains Nq t) = NoH t) for the activated quiescent nuclei number density, where H(t) is the Heaviside unit step function, zero for f < 0 and unity for t > 0. Then the rate of the nuclei number density is Ng = NoS t), with (5(f) being the Dirac delta function concentrated at f = 0. Equations 4.1 and 4.3 lead to the familiar Avrami equation ... 

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