Direct calculation of the ionic mobility in superionic conductors.

Area of Science:

• Materials Science
• Computational Chemistry
• Solid-State Physics

Background:

• Accurate calculation of ionic mobility is crucial for developing advanced solid electrolytes.
• Existing methods like diffusion calculations often rely on approximations (e.g., non-interacting ions).
• First-principles calculations offer high accuracy but can be computationally expensive.

Purpose of the Study:

• To present a novel, computationally efficient method for calculating ionic mobility in solid ion conductors.
• To validate the proposed method by comparing its results with diffusion calculations and experimental data.
• To demonstrate the method's capability in capturing ion-ion correlations.

Main Methods:

• Non-equilibrium molecular dynamics (NEMD) simulations applied to finite slabs of solid materials.
• Application of an external electric field to observe the dynamic response of mobile ions.
• Comparison of NEMD results with diffusion calculations (non-interacting ion approximation) and experimental data.

Main Results:

• The NEMD approach provides good quantitative estimates for ionic mobilities.
• Successfully applied to silver conductors, specifically $\alpha$-AgI and $\alpha$-RbAg$_{4}$I$_{5}$.
• Demonstrates accuracy comparable to diffusion calculations and experimental values.

Conclusions:

• NEMD simulations offer a convenient, numerically robust, and accurate method for determining ionic mobility in solid electrolytes.
• This approach effectively accounts for ion-ion correlations at a reduced computational cost.
• The method shows significant promise for the design and optimization of solid ion conductors.