Abstract: In this paper, we propose a new method to deal with the rotationally inelastic scattering of the A+B Ccollison system.We neglect the off-diagonal elements in the coupled potential terms and fit the Morse potential to the Lennard-Jones potential by making them being equal to each' other at the zero and deepest points.Then we can obtain the two analytical solutions of the decoupled equations.Asymptotic analysis shows that they correspond to the incident and outgoing waves, respectively.The overall wavefunction is expanded by the two solutions.The S-matrix can be obtained by solving the linear equations.The results obtained from this method prove to be better than those from IOScompared with the exact CCresults.

Key words: Rotationally inelastic scattering, Lennard-Jones potential, Morse potential, Scattering matrix