H-H dipole interactions in fcc metals

TL;DR

This paper investigates the electromagnetic dipole interactions among interstitial hydrogen nuclei in fcc metals, revealing potential new low-temperature phases and effects on Coulomb barriers through numerical analysis.

Contribution

It demonstrates that dipole-dipole interactions dominate hydrogen coupling in metals and predicts a novel low-temperature phase in PdD based on superposition states.

Findings

Identification of dominant dipole-dipole interactions

Existence of lower-energy superposition states in PdD

Potential narrowing of Coulomb barriers at small separations

Abstract

It is observed that interstitial hydrogen nucleii on a metallic lattice are strongly coupled to their near neighbours by the unscreened electromagnetic field mediating transitions between low-lying states. It is shown that the dominant interaction is of dipole-dipole character. By means of numerical calculations based upon published data, it is then shown that in stoichiometric PdD, in which essentially all interstitial sites are occupied by a deuteron, certain specific superpositions of many-site product states exist that are lower in energy than the single-site ground state, suggesting the existence of a new low temperature phase. Finally, the modified behaviour of the two-particle wavefunction at small separations is investigated and prelimary results suggesting a radical narrowing of the effective Coulomb barrier are presented.