Voltage equilibration for reactive atomistic simulations of electrochemical processes

Area of Science:

• Computational materials science
• Physical chemistry
• Nanotechnology

Background:

• Accurately modeling electrochemical driving forces is crucial for understanding and designing electrochemical devices.
• Existing reactive molecular dynamics methods often struggle to incorporate the dynamic effects of applied potentials and charge equilibration.

Purpose of the Study:

• To introduce a novel computational model, electrochemical dynamics with implicit degrees of freedom (EChemDID), for reactive molecular dynamics.
• To enable the simulation of electrochemical potentials and their influence on partial atomic charges within metallic systems.
• To provide a tool for investigating electrochemical reactions and device operation at the atomic scale.

Main Methods:

• Developed EChemDID, incorporating an additional variable for local atomic potential and using fictitious dynamics for its equilibration.
• Integrated the local electrostatic potential to dynamically adjust atomic electronegativities for charge equilibration calculations.
• Validated the model by simulating electric fields, electrochemical reaction driving forces, and electrochemical metallization cell operation.

Main Results:

• EChemDID accurately describes electric fields generated by applied voltage and the driving forces for electrochemical reactions.
• Simulations of electrochemical metallization cells successfully predicted device switching between high and low resistance states.
• Predicted resistive currents align with experimental measurements, validating the model's predictive power.

Conclusions:

• EChemDID offers a robust method for incorporating electrochemical effects into reactive molecular dynamics simulations.
• The model accurately captures the interplay between applied potentials, charge distribution, and atomic interactions.
• EChemDID has significant potential for applications in nanoelectronics and electrochemical energy conversion devices.