  We show from exact calculations that a simple tight-binding Hamiltonian with
diagonal disorder and long-range hopping integrals, falling off as a power
$\mu$ of the inter-site separation, correctly describes the experimentally
observed amplitude (close to the value of an ordered ring) and flux-periodicity
($hc/e$) of persistent currents in single-isolated-diffusive normal metal rings
of mesoscopic size. Long-range hopping integrals tend to delocalize the
electrons even in the presence of disorder resulting orders of magnitude
enhancement of persistent current relative to earliar predictions.
