Computational methods for intramolecular electron transfer in a ferrous-ferric iron complex.

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Theoretical Chemistry

Background:

• Predicting electron transfer is crucial in chemistry and biology.
• Common computational methods have limitations in accuracy.
• Accurate prediction requires careful consideration of electronic and solvent effects.

Purpose of the Study:

• To evaluate limitations of theoretical and molecular computational approaches for electron transfer.
• To investigate basis set effects on electronic coupling.
• To explore methods for calculating solvent reorganization energy.

Main Methods:

• Quasi-diabatic method for electronic coupling.
• Marcus continuum model with Born-Kirkwood-Onsager correction.
• Conductor-Like Screening Model (COSMO) for solvent effects.
• Explicit solvent molecular dynamics simulations.
• Analysis of solvent response and reorganization entropy.

Main Results:

• Basis set errors can significantly impact electronic coupling calculations.
• COSMO provides accurate solvent reorganization energy estimations, comparable to molecular dynamics.
• Dielectric saturation in the solvation layer affects potential energy surface curvature.
• Solvent reorganization entropy influences electron transfer rates.
• A method for estimating vibrational frequencies and isotopic signatures was developed.

Conclusions:

• Computational accuracy for electron transfer depends on basis set choice and solvent models.
• COSMO is a viable and efficient alternative for solvent reorganization energy calculations.
• Understanding solvent dynamics is key to accurately predicting electron transfer rates and isotopic effects.