Abstract: The vector correlations between products and reagents for the reactions Ne+H$_{2}^{ + }$, Ne+D$_{2}^{ + }$, and Ne+T$_{2}^{ + }$ are calculated by means of the quasi-classical trajectory method on a new potential energy surface constructed by Lü et al. [J. Chem. Phys. 2010 132, 014303]. The polarization-dependent differential cross-sections ($2\pi /\sigma )({\rm d}\sigma _{00}/{\rm d}\omega _{t})$, ($2\pi /\sigma )({\rm d}\sigma  _{20}/{\rm d}\omega _{t})$, ($2\pi /\sigma )({\rm d}\sigma_{22+} /{\rm d}\omega _{t})$, and ($2\pi /\sigma )({\rm d}\sigma _{21 - }/{\rm d}\omega _{t})$, and the distributions of $P(\theta _r)$, $P(\phi _r )$, and $P(\theta _r$, $\phi _r)$ are  calculated. The isotopic effect, which is associated with the difference in mass factor among the three reactions, is revealed.

Key words: stereodynamics, quasi-classical trajectory, isotoπc effect, vector correlation