Above Saddle-Point Regions of Order in a Sea of Chaos in the Vibrational Dynamics of KCN

Abstract

The dynamical characteristics of a region of regular vibrational motion in the sea of chaos above the saddle point corresponding to the linear C-N-K configuration is examined in detail. To explain the origin of this regularity, the associated phase space structures were characterized using suitably defined Poincaré surfaces of section, identifying the different resonances between the stretching and bending modes, as a function of excitation energy. The corresponding topology is elucidated by means of periodic orbit analysis.

Phase-space resolved rates in driven multidimensional chemical reactions

“…For example, the rank-1 barrier in between the two (meta)-stable conformations in the LiCN ↔ LiNC isomerization reaction may be an easy example to test the methods presented here. An application to KCN 45 or Ketene 20 is also conceivable, but since these systems contain more than one barrier in between their reactant and product states, the dynamics is expected to be much more complex and chaotic.…”

Controlling reaction dynamics in chemical model systems through external driving

“…To achieve this goal, however, it is required to extend the methods discussed here to models explicitly describing particular chemical reactions. Promising candidates include the isomerization reactions of LiCN [53][54][55][56], KCN [57,58], and ketene [59][60][61][62][63]. Additionally, the results have to be extended to include noise and friction (i. e. Langevin dynamics) in order to be applicable to real chemical reactions.…”

Dynamics and decay rates of a time-dependent two-saddle system

“…That chemical reactions can be represented with potentials exhibiting the challenges discussed here, is illustrated by the isomerization of ketene via formylmethylene and oxirene which has been modeled via a four-saddle potential [32,[58][59][60][61]. The isomerization reaction of triangular KCN via a metastable linear K-CN configuration can similarly be described by a two-saddle system [62,63]. Thus the analysis of time-dependent driven potentials resolved here, when applied to these and other chemical reactions, should provide new predictive rates for driven chemical reactions of interest.…”