The investigation of atom diatom scattering by using a wave packet method with parallel programming

The dynamics and kinetics of the Li + H2+ reaction and its isotopic variants (D2+ and T2+) have been studied by using a time-dependent wave packet (TDWP) coupled-channel (CC) method on the ab initio potential energy surface (PES) of Martinazzo et all. Total initial v=0, j= 0 state-selected reaction probabilities for the Li +H2+ reaction and its isotopic variants have been calculated from the threshold up to 1 eV for total angular momenta J from 0 to 90. Integral cross sections have been evaluated from the reaction probabilities at collision energies from threshold (?0,2 eV) up to 1,0 eV collision. The calculated rate constants as a function of temperature show an Arhenius type behavior in the 200K - 1000 K temperature interval. It has been found to be a considerable large intermolecular kinetic isotope effect. The TDWP-CC results are in overall good agreement with those obtained applying the TDWP Centrifugal-Sudden (CS) by approximation, showing that the CS approximation is rather accurate for the title reaction.H+ + LiH reaction have been studied using a quantum reactive time-dependent wave packet (TDWP) coupled-channel quantum mechanical method on an ab initio potential energy surface at conditions of the early universe. The total reaction probabilities for the H+ +LiH(v=0,j =0)?H2++ Li process have been calculated from 5×10?3 eV up to 1 eV for total angular momenta J from 0 to 110. Using a Langevin model, integral cross sections have been calculated in that range of collision energies and extrapolated for energies below 5×10?3 eV. The calculated rate constants are found to be nearly independent of temperature in the 10?1000 K interval with a value of ?10?9cm3s?1, which is in good agreement with estimates used in evolutionary models of the early universe lithium chemistry.Key words: Reaction probabilities, Centrifugal-Sudden (CS) approximation, Cross-sections, Rate constants, Langevin model, Astrochemistry ? Early universe.