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How can computational chemistry software be used to model transition states?

In my research on reaction mechanisms, I often encounter proposed transition states that are experimentally elusive. I'm looking for guidance on which software tools and computational approaches are most reliable for modeling these fleeting, high-energy structures to validate our mechanistic hypotheses.

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By Seema Answered 1 year ago

From my experience, modeling transition states is about choosing the right tool for the job. I typically start with Density Functional Theory (DFT) in software like Gaussian or ORCA to optimize the geometry and locate the saddle point. The key is to verify it with a frequency calculation to confirm one imaginary vibration mode, which is the "fingerprint" of a true transition state. I would also recommend running an Intrinsic Reaction Coordinate (IRC) calculation to confirm it connects your intended reactants and products. This workflow has been indispensable for validating mechanisms in my own projects.

 

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