1999/09/01 by Germán Sierra, G. Sierra, J. Dukelsky +4 · 3 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Physics of Superconductivity and Magnetism #Superconductivity in MgB2 and Alloys #cond-mat.supr-con #nucl-th
paper · pdf · doi:10.1103/physrevb.61.r11890
published as Phys.Rev. B61 (2000) 11890 · 4 pages, 3 eps figs, RevTex
arxiv created 1999/09/01 · openalex publication_date 2000/05/01 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The reduced BCS model that is commonly used for ultrasmall superconducting grains has an exact solution worked out long ago by Richardson in the context of nuclear physics. We use it to check the quality of previous treatments of this model, and to investigate the effect of level statistics on pairing correlations. We find that the ground-state energies are on average somewhat lower for systems with nonuniform than uniform level spacings, but both have an equally smooth crossover from the bulk to the few-electron regime. In the latter, statistical fluctuations in ground-state energies strongly depend on the grain's electron number parity.