Spectral Statistics of Mesoscopic Wires: Crossover from Wigner-Dyson to Poisson Regime

We calculate the density of states autocorrelation function $K(L,\omega )$ of a quasi-one-dimensional wire for practically all relevant values of the sample length $L$ and the energy separation ω. As a result we obtain an overview including known types of spectral correlations for $L$ smaller than the localization length ξ, novel spectral behavior emerging in the localized regime, $L\gg \xi$, and Poisson statistics in the thermodynamic limit. The analysis is performed within the framework of the supersymmetric nonlinear σ model.