Charge constrained density functional molecular dynamics for simulation of condensed phase electron transfer...

Area of Science:

• Computational chemistry
• Quantum chemistry
• Chemical physics

Background:

• Electron transfer reactions are fundamental in chemistry and biology.
• Accurate simulation requires methods that handle charge redistribution and solvation dynamics.
• Previous methods often struggle with the precise energetic costs of these reactions.

Purpose of the Study:

• To implement and validate a plane-wave basis set version of charge constrained density functional molecular dynamics (CDFT-MD).
• To accurately simulate electron transfer reactions in condensed phase systems.
• To calculate the reorganization free energy for the Ru2+-Ru3+ electron self-exchange reaction.

Main Methods:

• Developed a plane-wave basis set implementation of CDFT-MD.
• Minimized density functional energy under charge difference constraints.
• Propagated classical ion dynamics on the Born-Oppenheimer surface.
• Applied the method to the Ru2+-Ru3+ aqueous system.

Main Results:

• Obtained a reorganization free energy of 1.6 eV for the Ru2+-Ru3+ reaction.
• This value is lower than previous estimates using continuum solvation models.
• The difference is attributed to more similar Ru-O bond lengths in the electron transfer complex.

Conclusions:

• CDFT-MD provides a more accurate description of electron transfer energetics than continuum models.
• The method captures crucial structural changes during electron transfer.
• This work advances the simulation of charge transfer processes in solution.