High-temperature effects for transition state calculations in solids.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Materials Science

Background:

• Transition state calculations are vital for understanding solid-state dynamics.
• Using 0 K transition state data for high-temperature phenomena introduces unknown errors.
• Accurate prediction of high-temperature dynamical processes in solids requires accounting for temperature effects.

Purpose of the Study:

• To benchmark the impact of major temperature effects on defect diffusion in solids.
• To evaluate the accuracy of 0 K transition state calculations for high-temperature dynamics.
• To identify the dominant temperature-dependent factors influencing defect diffusion.

Main Methods:

• Employed first-principles calculations to evaluate temperature effects.
• Included lattice expansion, lattice vibration, electron excitation, and band-edge shift.
• Calculated defect formation energies, hopping barriers, and attempt frequencies.

Main Results:

• Inclusion of temperature effects significantly reduces discrepancies between theoretical and experimental diffusivities.
• Lattice expansion and vibration are dominant factors lowering defect formation energies and hopping barriers.
• Electron excitation has minor effects, while band-edge shift is significant for semiconductors.

Conclusions:

• Temperature effects, particularly lattice expansion and vibration, are crucial for accurate high-temperature defect diffusion predictions.
• Attempt frequencies vary significantly across materials (e.g., Al vs. 4H-SiC) due to temperature effects.
• This work provides a framework for more accurate prediction of dynamical processes in solids at elevated temperatures.