Theoretical Calculation of Vector Correlations for the Reaction

Abstract

The stereodynamics of the reaction $H(^2S) + NH$ $(v= 0, 1, 2, 3; j = 0)→$$N(^4S) + H_2$ are studied using the quasi-classical trajectory method on a double many-body expansion potential energy surface to understand the alignment and orientation of the product molecules in the collision energy range of 2–20 kcal·${\rm mol}^{−1},$ The vibrational–rotational quantum number of the NH molecules is specifically investigated for $v = 0, 1, 2,$ and $3$ and $j = 0.$ The $P(\theta_r),$ $P(\phi_r ),$ $P(\theta_r ,\phi_r ),$ differential cross section [DCS; ($2\pi\sigma)$$(d\sigma_{00}/dw_t)],$ and average rotational alignment factor $〈P_2({\rm cos}\theta_r)〉$ are calculated. The stereodynamics results indicate that the reagent vibrational quantum number and initial collision energy significantly affect the distributions of the $k–j',$ $k–k'–j'$ and $k–k'$ vector correlations along with $〈P_2({\rm cos} \theta_r)〉.$ In addition, while DCS is extremely sensitive to the collision energy, it is not significantly affected by the vibrational excitation of the reagents.