The contribution of the nature of potential energy surface (PES) on quantum mechanical tunneling have been investigated for a series of hydrogen atom transfer (HAT) reactions at state-of-the-art composite CBS-QB3 and modified G4MP2 method. Two series of HAT reactions have been considered to get different kinds of PES e.g., (i) HAT from different substrate by same radical abstractor and (ii) HAT from same substrate by different radical abstractor. It has been found that approximately more than 90% of the overall reactions have been proceeds through tunneling path even at room temperature (298 K) for all the investigated reactions. The symmetric i.e., thermo-neutral PES possesses more tunneling than the asymmetric i.e., exothermic or endothermic PES. It is due to the higher degree of overlap between reactant and product wave-function in symmetric PES which facilitates to cross the barrier through tunnel. Both CBS-QB3 and G4MP2 results provides similar kind of trend.

在最新的复合CBS-QB3和改进的G4MP2方法下，针对一系列氢原子转移（HAT）反应，研究了势能表面（PES）的性质对量子力学隧穿的影响。已经考虑了两个系列的HAT反应来获得不同种类的PES，例如（i）来自同一底物的自由基分离剂的不同底物的HAT和（ii）来自不同底物的自由基提取物的同一底物的HAT。已经发现对于所有研究的反应，甚至在室温（298K）下，整个反应的大约90％以上已经通过隧穿路径进行。对称即热中性的PES比不对称即放热或吸热的PES具有更多的隧穿。这是由于对称PES中反应物和产物波函数之间的重叠程度较高，这有助于通过隧道穿越势垒。CBS-QB3和G4MP2结果都提供了类似的趋势。