Tunnel Effects in the H + D$_2$ and D + H$_2$ Reactions

다국어 초록 (Multilingual Abstract)

We considered the tunneling effect on the rate constants calculated from transition-state theory for the H + $D_2$ and D + $H_2$ reactions. A method for evaluating the important parameter Ec (potential barrier height) was proposed. A tunnel-effect correlation factor (TECF) ${\Gamma}_{t}exp{\theta}_t$ was estimated from experimental data, and compared with the corresponding values obtained from many theoretical methods. According to our results, the tunneling effect cannot be negligible around $800^{\circ}$K where the TECF value is ca. 0.8 whereas the factor approaches to unity at T > $2400^{\circ}$K where the tunneling completely disappears. In addition to the above fact, we also found that the TECF for the D + $H_2$ reaction is greater than that of the H + $D_2$ reaction in agreement with Garrett and Truhlar's result. In contrast to our result, however, Shavitt found that the order is reversed, i.e., TECF for (D + $H_2$) is greater than that for (H + $D_2$). We discussed about the Shavitt's result.