y Path integral study on C15-type Laves TiCr2 hydride

The path integral method has been applied for the C15-type Laves alloy hydride, TiCr2H1.3, to treat quantum mechanical effects on atomic nuclei. The atomic interaction is simulated by the machine learning potential which reproduces well the results of density functional calculations. The canonical ensemble is sampled using the hybrid Monte Carlo method at 300 K. The predicted heat of solution, - 19 kJ/molH(2), agrees well with the available experimental data. Hydrogen atoms dominantly occupy the 96g sites which form the closed hexagonal rings (HRs). Two H diffusion paths, the intra- and inter-HR paths, are identified, for which the activation barriers are evaluated to be 63 and 155 meV, respectively. They most likely correspond to different two H hopping modes assigned in the nuclear magnetic resonance experiment. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.