State of Hydrogen in BCC Metals: Its Quantum-Mechanical Character

A consistent quantum-mechanical description is given of some atomistic properties of hydrogen isotopes in bcc metals, including in particular the energy and wave functions of a hydrogen atom, its preference of the type of interstitial sites, distortion of the surrounding lattice, and its effects on crystal structure. A general systematics in the site-preference–a transition from T sites to O sites in more congested circumstances–is noted and explained physically. Results of our recent experiments on hydrogen in V and Fe are also presented.