document: In this Letter we revisit the Chesnavich model Hamiltonian [37] in the light of recent developments in TST. For barrierless systems such as ion–molecule reactions, the concepts of OTS and TTS can be clearly formulated in terms of well defined phase space geometrical objects. (For work on the phase space description of OTS, see Refs. [38–40].) The first goal of the present article is the identification of these notions with well defined phase space dividing surfaces attached to NHIMs. The second and main goal is an elucidation of the roaming phenomenon in the context of the Chesnavich model Hamiltonian. The associated potential function, possessing many features associated with a realistic molecular PES, leads to dynamics which clearly reveal the origins of the roaming effect. Based on our trajectory simulations, we show how the identification of the TTS and OTS DSs with periodic orbit dividing surfaces (PODS) provides the natural framework for analysis of the roaming mechanism.
doc_bio_tags: O O O O O O B I I O O O O O O O O B O O O O O B I O O O B O B O O O O O O O O O O B I I O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O B I I O B I I O O O O O O O O O O O B I I I I I I I I I O O O B I O O O O B O O B O B O O B I I I B O O O O O O O O O O
extractive_keyphrases: associated potential function chesnavich model hamiltonian dynamics which clearly reveal the origins of the roaming effect identification ion–molecule reactions nhims ots periodic orbit dividing surfaces pods space geometrical objects trajectory simulations tst tts
abstractive_keyphrases: well defined phase space dividing surfaces attached to nhims