Affiliation:
1. Department of Materials Science and Engineering, Southern University of Science and Technology 1 , Shenzhen 518055, China
2. Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology 2 , Shenzhen 518055, China
Abstract
Transition state calculation is a critical technique to understand and predict versatile dynamical phenomena in solids. However, the transition state results obtained at 0 K are often utilized for the prediction or interpretation of dynamical processes at high temperatures, and the error bars of such an approximation are largely unknown. In this benchmark study, all the major temperature effects, including lattice expansion, lattice vibration, electron excitation, and band-edge shift, are evaluated with first-principles calculations for defect diffusion in solids. With the inclusion of these temperature effects, the notable discrepancies between theoretical predictions at 0 K and the experimental diffusivities at high temperatures are dramatically reduced. In particular, we find that lattice expansion and lattice vibration are the dominant factors lowering the defect formation energies and hopping barriers at high temperatures, but the electron excitation exhibits minor effects. In sharp contrast to typical assumptions, the attempt frequency with lattice expansion and vibration varies significantly with materials: several THz for aluminum bulk but surprisingly over 500 THz for 4H-SiC. For defects in semiconductors, the band-edge shift is also significant at high temperatures and plays a vital role in defect diffusion. We expect that this study would help accurately predict the dynamical processes at high temperatures.
Funder
Guangdong Provincial Key Laboratory of Computational Science and Material Design
Introduced Innovative R&D Team of Guangdong
Science, Technology and Innovation Commission of Shenzhen Municipality
Subject
Physical and Theoretical Chemistry,General Physics and Astronomy