A Fast and Accurate Semi-Empirical Approach for Hydrogen-Exchange Kinetic Isotope Effect Evaluation

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Chemical Kinetics

Background:

• Kinetic isotope effect (KIE) is crucial for understanding reaction mechanisms and applications like tritium removal.
• Accurate KIE evaluation is computationally challenging, particularly in determining transition state geometries.
• Existing methods like DFT are computationally expensive and sensitive to the level of theory.

Purpose of the Study:

• To develop a novel, rapid, and precise semi-empirical method for KIE estimation.
• To address the computational difficulties associated with traditional KIE evaluation.
• To provide a computationally efficient and accurate alternative to DFT and conventional semi-empirical methods.

Main Methods:

• A novel semi-empirical approach for KIE estimation.
• Refinement of transition state identification using an iterative surface scan.
• Benchmarking against experimental data and comparison with DFT and other semi-empirical methods.

Main Results:

• The developed method demonstrates superior accuracy and computational efficiency compared to DFT and conventional semi-empirical methods.
• Validation with tritium exchange reactions confirms the robustness of the approach.
• The method successfully estimates KIE in proton-exchange reactions.

Conclusions:

• The novel semi-empirical method provides a significant advancement in KIE estimation for proton-exchange reactions.
• This approach offers a balance of accuracy and computational efficiency, overcoming limitations of existing methods.
• The freely available computational implementation will facilitate broader research integration.