A NOVEL NON-ACTIVE MODEL TO ACCOUNT FOR THE LEAK OF ZERO-POINT ENERGY IN TRAJECTORY CALCULATIONS - APPLICATION TO H+O2 REACTION NEAR-THRESHOLD

A novel non-active model to correct for the leak of zero-point energy in quasi-classical trajectory calculations is proposed. It consists of eliminating every trajectory that fails to satisfy the zero-point energy requirement of quantum mechanics at the end of the trajectory, and then correct the results using a unified statistical approach which takes into account the relative probabilities of the reactive and non-reactive events. The correction factor assumes a simple analytic form, adding no extra cost to the traditional quasiclassical trajectory approach. Test calculations are presented for the total reactivity of the H + O2 reaction out of the initial vibrational-rotational state (v, j) = (0, 0), keeping the total angular momentum J = 0. Comparison of the results with quantum mechanical reactivities calculated on the same (DMBE IV) potential energy surface shows good agreement. A possible generalization of the model to require a local zero-point energy along the trajectory is pointed out.