Calculations of the products angular polarization and the isotopic effect for the reactions Cl + CH4 and Cl + CD4 have been performed on a new London-Eyring-Polanyi-Sato potential energy surface (LEPS PES) via the quasiclassical trajectory method at the collision energy of 3.67 kcal/mol (0.16 eV). The calculations are in good agreement with the experimental results. The effect of the potential barriers on the chemical reactions and the isotope effect for the reactions Cl + CH4/Cl + CD4 are investigated. Comparison of the results of the new PES with two previous PESs shows that the different character of product rotational polarization and the increase of forward scattering are attributable to different potential barriers. (c) 2006 Elsevier B.V. All rights reserved.