First-Principles Calculation Of The Elastic Dipole Tensor Of A Point Defect: Application To Hydrogen In Alpha-Zirconium

The elastic dipole tensor is a fundamental quantity relating the elastic field and atomic structure of a point defect. We review three methods in the literature to calculate the dipole tensor and apply them to hydrogen in alpha-zirconium using density functional theory (DFT). The results are compared with the dipole tensor deduced from earlier experimental measurements of the lambda tensor for hydrogen in alpha-zirconium. There are significant errors with all three methods. We show that calculation of the lambda tensor, in combination with experimentally measured elastic constants and lattice parameters, yields dipole tensor components that differ from experimental values by only 10%-20%. There is evidence to suggest that current state-of-the-art DFT calculations underestimate bonding between hydrogen and alpha-zirconium.