Effect of Vacancies on Hydrogen Mobility and Trapping in Elemental Fe and Cr: A DFT and kMC Study
Abstract
Hydrogen-vacancy interactions play an important role in governing hydrogen transport and embrittlement in body-centered cubic (BCC) metals. In this study, a multiscale approach combining density functional theory (DFT) and kinetic Monte Carlo (kMC) simulations is employed to investigate hydrogen behavior in BCC Fe and Cr. The DFT-calculated binding energies and Bader charge analysis indicate stronger hydrogen trapping in Cr than in Fe. Migration and detrapping energy barriers are determined using the climbing-image nudged elastic band method, showing that the detrapping energy generally decreases with increasing hydrogen occupancy. However, the sixth hydrogen atom in Fe exhibits a finite barrier, contrary to some previous reports. kMC simulations are then used to evaluate hydrogen diffusion over extended time and length scales. The results demonstrate that vacancy defects significantly reduce hydrogen mobility and increase the effective activation energy, with a more pronounced effect observed in Cr due to stronger trapping. The combined DFT-kMC framework provides detailed insight into the mechanisms of hydrogen trapping, detrapping, and diffusion in BCC metals, offering important implications for understanding hydrogen embrittlement in structural materials.
Versions
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BibTeX
@misc{vallinathan2026effect,
title = {{Effect of Vacancies on Hydrogen Mobility and Trapping in Elemental Fe and Cr: A DFT and kMC Study}},
author = {Vallinathan K and Gurpreet Kaur and Sharat Chandra},
howpublished = {arXiv},
year = {2026},
month = may,
doi = {10.48550/arxiv.2605.27983},
eprint = {2605.27983},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.27983},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Effect of Vacancies on Hydrogen Mobility and Trapping in Elemental Fe and Cr: A DFT and kMC Study
AU - Vallinathan K
AU - Gurpreet Kaur
AU - Sharat Chandra
PY - 2026
DA - 2026/05/27
PB - arXiv
DO - 10.48550/arxiv.2605.27983
UR - https://arxiv.org/abs/2605.27983
AB - Hydrogen-vacancy interactions play an important role in governing hydrogen transport and embrittlement in body-centered cubic (BCC) metals. In this study, a multiscale approach combining density functional theory (DFT) and kinetic Monte Carlo (kMC) simulations is employed to investigate hydrogen behavior in BCC Fe and Cr. The DFT-calculated binding energies and Bader charge analysis indicate stronger hydrogen trapping in Cr than in Fe. Migration and detrapping energy barriers are determined using the climbing-image nudged elastic band method, showing that the detrapping energy generally decreases with increasing hydrogen occupancy. However, the sixth hydrogen atom in Fe exhibits a finite barrier, contrary to some previous reports. kMC simulations are then used to evaluate hydrogen diffusion over extended time and length scales. The results demonstrate that vacancy defects significantly reduce hydrogen mobility and increase the effective activation energy, with a more pronounced effect observed in Cr due to stronger trapping. The combined DFT-kMC framework provides detailed insight into the mechanisms of hydrogen trapping, detrapping, and diffusion in BCC metals, offering important implications for understanding hydrogen embrittlement in structural materials.
ER -