准经典轨线计算能否再现 H + H2 反应中观察到的μ同位素的极端动力学同位素效应？

Can quasiclassical trajectory calculations reproduce the extreme kinetic isotope effect observed in the muonic isotopologues of the H + H2 reaction?

机构信息

Departamento de Química Física, Facultad de Química, Universidad Complutense, 28040 Madrid, Spain.

出版信息

J Chem Phys. 2011 Jul 21;135(3):034310. doi: 10.1063/1.3611400.

Abstract

Rate coefficients for the mass extreme isotopologues of the H + H(2) reaction, namely, Mu + H(2), where Mu is muonium, and Heμ + H(2), where Heμ is a He atom in which one of the electrons has been replaced by a negative muon, have been calculated in the 200-1000 K temperature range by means of accurate quantum mechanical (QM) and quasiclassical trajectory (QCT) calculations and compared with the experimental and theoretical results recently reported by Fleming et al. [Science 331, 448 (2011)]. The QCT calculations can reproduce the experimental and QM rate coefficients and kinetic isotope effect (KIE), k(Mu)(T)/k(Heμ)(T), if the Gaussian binning procedure (QCT-GB)--weighting the trajectories according to their proximity to the right quantal vibrational action--is applied. The analysis of the results shows that the large zero point energy of the MuH product is the key factor for the large KIE observed.

摘要

已通过精确的量子力学 (QM) 和准经典轨迹 (QCT) 计算，在 200-1000 K 的温度范围内计算了 H + H(2) 反应的质量极端同位素（即 Mu + H(2)，其中 Mu 是 muonium，以及 Heμ + H(2)，其中 Heμ 是一个电子被一个负 muon 取代的 He 原子）的速率系数，并与 Fleming 等人最近报道的实验和理论结果进行了比较。[Science 331, 448 (2011)]。如果应用高斯-bin 处理程序 (QCT-GB)——根据轨迹与正确量子振动作用的接近程度对轨迹进行加权——则 QCT 计算可以重现实验和 QM 速率系数和动力学同位素效应 (KIE)，k(Mu)(T)/k(Heμ)(T)。结果分析表明，MuH 产物的零点能很大是观察到的大 KIE 的关键因素。