Second-order Saddle Dynamics in Isomerization Reaction
| Autor: | Upakarasamy Lourderaj, Manikandan Paranjothy, Komal Yadav, Richa Rashmi |
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| Rok vydání: | 2021 |
| Předmět: |
Physics
010304 chemical physics Ab initio 010402 general chemistry 01 natural sciences Potential energy Molecular physics Transition state 0104 chemical sciences Mathematics (miscellaneous) Reaction dynamics Saddle point 0103 physical sciences Potential energy surface Physics::Chemical Physics Isomerization Saddle |
| Zdroj: | Regular and Chaotic Dynamics. 26:119-130 |
| ISSN: | 1468-4845 1560-3547 |
| Popis: | The role of second-order saddle in the isomerization dynamics was investigated by considering the $$E-Z$$ isomerization of guanidine. The potential energy profile for the reaction was mapped using the ab initio wavefunction method. The isomerization path involved a torsional motion about the imine (C-N) bond in a clockwise or an anticlockwise fashion resulting in two degenerate transition states corresponding to a barrier of 23.67 kcal/mol. An alternative energetically favorable path ( $$\sim$$ 1 kcal/mol higher than the transition states) by an in-plane motion of the imine (N-H) bond via a second-order saddle point on the potential energy surface was also obtained. The dynamics of the isomerization was investigated by ab initio classical trajectory simulations. The trajectories reveal that isomerization happens via the transition states as well as the second-order saddle. The dynamics was found to be nonstatistical with trajectories exhibiting recrossing and the higher energy second-order saddle pathway preferred over the traditional transition state pathway. Wavelet based time-frequency analysis of internal coordinates indicate regular dynamics and existence of long-lived quasi-periodic trajectories in the phase space. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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