Boson enhancement of finite-temperature coherent dynamics for deuterium in metals

Abstract

Effects of coherent many-particle dynamics in providing local site density fluctuations at finite temperatures for hydrogen isotopes in metals are analyzed with tight-binding calculations based on a Hubbard Hamiltonian. These fluctuations increase with temperature, with average deuterium density, and with the magnitude of the site-to-site tunneling. Consequences of such density fluctuations for deuterium dynamics at high concentrations are evaluated within a self-consistent formulation for self-screening of the deuteron-deuteron interaction. This leads to a prediction of significant enhancement of diffusion at high concentration for bosonic species, and anomalous isotope effects for hydrogen diffusion. Extrapolation to the nuclear regime yields estimates of finite-temperature bosonic collective effects on the nuclear reaction rate between deuterons in stoichiometric PdD, yielding rates which are several orders of magnitude below recent experimentally inferred values.

Formation of Atomic Tritium Clusters and Bose-Einstein Condensates

“…Figure 3 compares the ground state energy per particle E 0 /N of (T↑) N clusters (pluses) with those of 4 He N clusters (using the LM2M2 potential [14], diamonds). This shows that (T↑) N clusters are even more weakly bound than 4 He N clusters with the same number of atoms.…”

“…The ground state properties of larger spinpolarized tritium clusters are also presented and compared with those of helium clusters. In 1976 [1], Stwalley and Nosanow suggested, based on statistical arguments, that the system of spin-polarized bosonic tritium atoms behaves "very much like 4 He". To the best of our knowledge, their arguments have not yet been tested by a microscopic quantum mechanical treatment.…”

“…Study of these trimers, which were prepared on the surface of large 4 He clusters, revealed that three-body effects are surprisingly important [3]. We are not aware, though, of any experimental or theoretical studies of larger spin-polarized atomic cluster systems.…”

Experimental and theoretical study of the radial density distributions of large3Hedroplets

“…A distinct peak is found at 84 amu which is due to Kr atoms which have been trapped in the droplet. Figure 2 shows log plots of the scattered intensity ͓on the ( 3 He) 2 ϩ mass͔ as a function of the scattering angle for droplets of five different sizes. The upper curve is measured with the secondary beam crossing the droplet beam, whereas the lower curve is measured with the secondary beam intersected by a flag.…”

“…[1][2][3] Being the only definitely liquid clusters they provide a uniquely gentle homogeneous and at the same time very cold matrix for high-resolution spectroscopy of single molecules or aggregates of molecules. [4][5][6] Recent experiments have used the highly resolved spectra of single embedded molecules to probe the physical properties of the droplets.…”