Quasi-classical Trajectory Study Of The Vector Correlations For The Reaction Li+HFâ†'LiF+H

With the development of the mutual interaction between experiments and theories,molecular reaction dynamics has made great progress in recent decades, reaching thestate-to-state stage. Stereodynamics, as a new frontier branch in the area of molecular reactiondynamics, attracting great interest of many research groups,has been developed greatly andbecome a researching focus in the last two decades. As a classical atom-diatom reaction, Li+HFreaction has been extensively researched, getting achievements not only in experiment but alsoin theory. In principle, the three atoms Li, H and F are three lightest atoms in three differentmain groups, respectively. Moreover the three atoms have the least electronics in theircorresponding main groups. The less numbers of electronics are important premises to constructan accurate ab initio PES （Potential Energy Surface）. Thus it can provide a favorable protectionfor an accurate stereodynamical calculation. Therefore, we based on the ground state potentialenergy surface （PES） in2003, explore the reaction Li+HFâ†'LiF+H, using the quasi-classicaltrajectory method. The error of the potential energy surface is about0.515kcal/mol. While thesystem contains several interesting features：there exists a well in the entrance channel due tothe strong dipole electric fields of the reactants. Meanwhile，a late barrier and a relativelyshallow well in the H+LiF products channel, which determine the dynamic properties. The firstchapter briefly describes the dynamics of the development process, and the second chapterdescribes the theoretical methods, and the third chapter describes the background and the courseof development of the Li+HF reaction system.The fourth chapter is the main part of this paper. Firstly, The detailed stereodynamics ofthe reaction Li+HF（v=0³ï¼‰ at different collision energy and different vibration excited state hasbeen carried out by using the quasi-classical trajectory （QCT） method. The correlated k-j’,k-k-j angular distributions and the polarization dependent differential cross sections （PDDCSs）are discussed in detail. The results indicate that the collision energy has more impact on theP （θ_r）distributions describing the k-j’ correlation than the vibration excitation. Thedistributions of P（φ_r）describing the k-k’-j’ correlation as well as the polarization-dependent generalized differential cross sections are sensitive to the vibration excitation. Meanwhile, thecollision energy has also more influence on it.Secendly, we will introduce the vector correlations for the three reactionsLi+HF/DF/TF,which have been investigated in detail by the QCT method at different collisionenergies. The results indicate that the rotational angular momentum vectors j of the productsare mainly oriented along the negative Y axis while they are slightly aligned along Y axis.When the H atom is substituted by D and T, the orientation effect weakens, while the alignmenteffect changes little. Furthermore, the change of collision energies hardly influences eitherorientation or alignment effects. Therefore, we can draw the conclusion that the isotopesubstitution has more impact on the distribution of the product’s angular momentum vectorsthan the collision energy. Subsequently, we explore the polarization dependent differential crosssections. The calculated PDDCSs with q=0indicate that the product is almost exclusivelybackwards scattering, however, the trend becomes weaker with the increase of collision energyand becomes stronger with the isotope substitution. The results with q≠0show that thepolarization of the product rotational angular momentum vector presents differentcharacteristics. With the isotope substitution and the collision energy alteration, thePDDCS (dσ_21-/dω_t) hardly changes while the PDDCS （2Ï€/σ）(dσ₂₂₊/dω_t)showsobvious side scattering.