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Talk:MRD:cej15

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Good work! Let me give you a couple of pointers to improve further. I assume you ran out of time since a number of answers are missing and will concentrate on feedback of the questions you have answered.

  • TS properties: The graphic you used is correct, but a 1D representation of the PES. We're dealing with a 2D problem here (with two gradients and three curvatures). How can you generalise the definition of a saddle point in 1D to 2D? Think about what the reaction coordinate in your second figure represents on the PES.
  • Finding the TS: Your method is only valid for reactions where the products and reactants are the same (which are typically restricted to models, since a chemist usually wants to transform one substance into another). At the TS, reactants and products are balanced. By themselves, they will form neither reactants nor products. Can you use this to come up with a new method?
  • Reaction trajectories: Did you realise that you can change the time frame of your calculations? A lot of your trajectories can't be classified as reactive or unreactive because you didn't let enough time elapse.
  • MEP: What does the "wiggle" in the black line represent physically? What is the basis of the MEP calculations, i.e. how is the calculation of the force modified to get the MEP?
  • H-H-H trajectories: Your fourth table entry says "reactive", but your description indicates that the products weren't formed. I'll take this as a typo and you mean "unreactive".
  • TS theory: How does this relate to your findings? How does TS theory predictions compare to experimental values (not simulations)?
  • Exothermicity: You cannot determine whether a reaction is exothermic or endothermic by looking at an arbitrary trajectory. Exothermicity is determined by the geometry of the products vs. that of the reactants. Therefore, the shape of the entire PES tells you about exothermicity, not a specific path on the PES. The specific trajectory only tells you whether a set of initial conditions is reactive, not whether energy is released when the reaction is successful.
  • Activation Energies: Are the geometries you obtained for the reactants and products the final geometries? What would happen if you extended the timeframe of your reactions?
  • F-H-H trajectories: You need to increase the timeframe. These trajectories are not conclusive; they could potential be successful.--Bg1512 (talk) 14:46, 16 May 2017 (BST)