A molecularly based theory for electron transfer reorganization energy

Area of Science:

• Physical Chemistry
• Computational Chemistry
• Chemical Physics

Background:

• Charge solvation is crucial for understanding electron transfer reactions.
• Traditional methods often approximate solvents as linear dielectric media, limiting accuracy.
• Molecular details of solvent-charge interactions are vital for precise energy calculations.

Purpose of the Study:

• To develop a molecularly based dipolar self-consistent-field theory (DSCFT) for charge solvation.
• To apply DSCFT to calculate reorganization energies in electron transfer reactions under equilibrium and nonequilibrium conditions.
• To provide a more accurate theoretical framework than linear dielectric models.

Main Methods:

• Utilized field-theoretic techniques to formulate the dipolar self-consistent-field theory (DSCFT).
• Incorporated molecular parameters like permanent dipole moment and polarizability.
• Solved a set of self-consistent equations to obtain electrostatic potential profiles and electric susceptibilities.

Main Results:

• DSCFT provides an analytical expression for free energy using equilibrium and nonequilibrium electrostatic potentials.
• The theory accurately predicts activation and reorganization energies for electron transfer between metallic ions without adjustable parameters.
• Eliminated the need to distinguish between inner- and outer-sphere solvent molecules for reorganization energy calculations.

Conclusions:

• DSCFT offers a molecularly accurate description of charge solvation and electron transfer.
• The theory's predictions align well with experimental and computational data.
• DSCFT reveals charge-dependent curvature in nonequilibrium free energy surfaces, challenging linear dielectric theory predictions.