Transition state barriers in multidimensional Marcus theory.

Area of Science:

• Physical Chemistry
• Theoretical Chemistry
• Chemical Physics

Background:

• Traditional Marcus theory describes single-particle transfer reactions using intersecting parabolas.
• Multidimensional Marcus theory extends this to multiple particle transfers, involving intersecting paraboloids.
• Transition state barrier energies are critical for calculating reaction rates.

Purpose of the Study:

• To determine when a simplified one-dimensional formalism is sufficient for multidimensional Marcus theory.
• To investigate the accuracy of the one-dimensional approach for calculating transition state barrier energies.
• To develop a procedure for accurate multidimensional barrier energy calculations.

Main Methods:

• Analytic calculations and numerical simulations were employed.
• The study focused on the intersection of paraboloids in multidimensional Marcus theory.
• A specific collective reaction coordinate was chosen for the one-dimensional reduction.

Main Results:

• A reduced one-dimensional treatment shows excellent agreement with exact multidimensional results.
• This agreement holds across various conditions for a chosen reaction coordinate.
• A procedure for calculating accurate multidimensional barrier energies was outlined.

Conclusions:

• A simplified one-dimensional formalism can effectively approximate multidimensional Marcus theory under specific conditions.
• The reduced model accurately predicts transition state barrier energies.
• The findings are applicable to systems like proton-coupled electron transfer.