Stereodynamic origin of mode selectivity in the \(\textbf{NH}_{3}\) \(\varvec{+}\) F \(\varvec{\longrightarrow}\) \(\textbf{NH}_{2}\) \(\varvec{+}\) HF reaction

The hydrogen abstraction of ammonia by fluorine radical exhibits a peculiar mode selectivity as the ammonia inversion mode promotes the reaction more efficiently than the stretching mode. Although there were attempts to explain it in the literature, a precise understanding of the mode selectivity of this reaction is missing. In this work, using on-the-fly semi-classical trajectory calculation and quantum chemical computation, we have shown that the peculiar mode selectivity of the title reaction has a stereodynamic origin.