Transition to Ohmic conduction in microscopic tunnel junctions at low temperatures

The crossover from weak to strong coupling in tunneling is studied by relating the effective dc conductance to the susceptibility of the one-dimensional plane rotator model with 1/${\mathit{n}}^2$ interaction. The susceptibility and specific heat, all calculated using Monte Carlo simulation, confirm the existence of a precipitous breakdown of the Coulomb blockade for the ratios of thermal to charging energy as small as ${10}^{\mathrm{-}3}$.